[thenewoldschool]

Hello Guys,
New to e90post / N55's, but long time bimmer fan here- I actually drive an E39 M5 right now but am doing my prelim research to cross over into an E92 335i N55 6-speed next. I'm excited because this will be my first turbo car ever.

I have been doing a lot of research and reading but find myself with a few main questions that I am still looking for answers to and was hoping you guys can help. Also, a lot of the posts are several years old and I am not sure if new developments have occurred. Please note, I am very skeptical and scientific in my approach, I like to see hard numbers in order to make relevant comparisons (ie. talking about measurable differences on a dyno or some other method). Questions are as follows:

#1: V-Band Flange- are these all the same size for the aftermarket DP's? I would assume so, as it needs to clamp to the same turbo exhaust manifold. I ask because I have seen different sized catted DP's, and by themselves without reference it is really difficult to tell (for example, the AR Designs on x-ph.com is stated to have a 4" body, yet from the stock photo it looks like the V-Band Flange is the same diameter as the 4" body?)

#2 I have seen a few mentions of the AR DP as the "only 5" downpipe" for the N55, however x-ph.com seems to indicate it as a 4"? The CP-e is stated to be 5", I am assuming it is newer. Just confirming specs- I have a suspicion the N55 AR DP has changed since it first came out

#3 Cells- I have heard whispers of people suggesting a 300 cell downpipe, I have not actually seen any advertised with 300, only 200. Is there any chart or source that compares cell count? Only a couple even mention their cell count. Is this a universal measurement derived off cat diameter, or do the cell designs vary?

#4 Flow Testing- not seat of pants! Either by dyno or flow bench, are there any direct comparisons between the different downpipes? I would assume the size of the cat would make the biggest difference. Is there a direct correlation across all brands? Or does someone's (4", for example) flow better than other (4") DP's on the market? It is only logical to me that flanges for all of the DP's are the same, so for a catted DP the only (significant) difference between any of them that I can tell is the cat element itself.

#5 Emissions and Longevity - this one is super important to me! I live in California (insert unilateral groan from everyone NOT from California) and as we all know cats are required. I have seen mention that some are prone to fail quickly and throw CEL light (have heard ER does this). Does anyone know which catted DP's last the longest? Are there any that are known for NOT throwing codes or going bad? Are there any that are actually CA E.O. / CARB certified? (Because I haven't seen an EO on any of them) Or is there some law/exception that if they pass the OBD and sniffer it doesn't need EO stickers? The discussions over this have been vague, and CA smog laws have changed recently.

#7 ER DP for E92? I've seen people talk about the ER DP, haven't seen it for the coupe though- doesn't fit that application, or have I just missed it?

#6 Cat-Back exhaust: I am seeing 2 main types of PE systems, either dual 2.5" piping back from the DP, or a 3" converged single pipe. I am generally under the approach that if I go down to a single pipe, I don't want to split it back up again at the muffler- and by that same approach, I generally don't like the idea of the DP necking down to a single tube, then splitting to a dual outlet, just to merge back again (like on a Cobb 3" cat-back for example). For this reason I am leaning heavily towards Magnaflow (I have used them on a number of my cars and have always been pleased). The area of a 3" circle is ~7 square inches, whereas 2x 2.5" is 9.8 (and the 2x 2.25" being 7.9, almost the same as the single 3"), for that reason I would assume the Magnaflow would produce a better top end than the Cobb, with Cobb producing more torque and possibly less lag in the bottom end. Is there a clear style that the N55 seems to prefer? Or pipe diameter? No sense in having huge cat-back pipes that way out flow the DP, I want to keep everything balanced. I will explain my build below the questions, but if there are any systems out there that CLEARLY excel over the others in terms of flow and performance, I'm interested. From a sound approach, on basically every car I've ever compared I have always liked the sound of Magnaflow, and had them on my 350ci Chevy Nova and Datsun 240Z.

#6.5 - do any cat-backs maintain mid section cats? Haven't seen any but for peace of mind would definitely consider.

#7 Extra bungs? Needed?


The platform I am looking for:
2011-2013 335i Coupe, 6-speed preferably with M-Sport package (Blue, Silver, White or Black, in that preference order). Hopefully with tan seats (maybe red depending on paint).

Planned upgrades, in order of priority / install:
-ER Competition dual oil coolers
-Burger oil catch can
-Massive intercooler (unsure which brand, looking at VRSF 7.5" step race IC, open to suggestions. I want max charge cooling, willing to do light modification but nothing crazy, I'm unsure on the fit of the stepped 7.5", also looking at ETS 7", Wagner actually looks like an 8"?, ER's seems smallest of these, Active Autowerke doesn't have dimensions but looks big/tall, Cobb also seems on the smaller side out of these)
-Tune- likely Vishnu PROcede Rev3, but maybe BMS JB4- again, open if there is a clear choice for choosing one over the other (I would like the following pre-sets: an "economy" mode for absolute best mpg, a "max performance" mode which will be my usual setting, a "max performance with meth" tune when I want to turn on the system and get spunky running 33% or 50% meth, and a completely stock mode)
-Charge Pipe - these don't seem to vary too much, I just want to replace the plastic one and get that meth bung
-Cat-back, probably Magnaflow unless I find a reason not to
-Pure Stage 1 turbo and previously discussed down pipe
-Meth injection kit- probably Vishnu, I like the windshield washer conversion and onlly intend to occasionally use the car with meth activated
-Quiafe 3.42 limited slip
-Fully ducted front brakes and stainless steel lines
-Vented hood and CSL style trunk
-Larger squared wheels and tires

From the builds that I have seen online, this build while spraying meth should be able to reasonably put down 400rwhp- it would be awesome if it could hit this WITHOUT the meth, but on stock internals running 91 octane I'm thinking my max will be closer to the 375 range prior to spraying. Torque will obviously be more, which is why I am probably keeping the conservative gearing- this will be my daily driver, which I always build with "high speed touring" approach with a heavy emphasis on reliability, hence the oil coolers being the #1 thing I am going to spend money on. The purpose in upgrading the turbo is it seems the Pure Stage 1 is going to be more durable, but will also give me the boost to be able to pull hard entirely through redline without sacrificing any low end lag. It is my understanding that the Stage 2 MUST be used in conjunction with meth, and as I only want to spray occasionally and not leave it on all the time, I don't see myself ever making the leap to the Stage 2.

Thanks for any input!

[STR8-6IX]

Originally Posted by thenewoldschool

Hello Guys,
New to e90post / N55's, but long time bimmer fan here- I actually drive an E39 M5 right now but am doing my prelim research to cross over into an E92 335i N55 6-speed next. I'm excited because this will be my first turbo car ever.

I have been doing a lot of research and reading but find myself with a few main questions that I am still looking for answers to and was hoping you guys can help. Also, a lot of the posts are several years old and I am not sure if new developments have occurred. Please note, I am very skeptical and scientific in my approach, I like to see hard numbers in order to make relevant comparisons (ie. talking about measurable differences on a dyno or some other method). Questions are as follows:

#1: V-Band Flange- are these all the same size for the aftermarket DP's? I would assume so, as it needs to clamp to the same turbo exhaust manifold. I ask because I have seen different sized catted DP's, and by themselves without reference it is really difficult to tell (for example, the AR Designs on x-ph.com is stated to have a 4" body, yet from the stock photo it looks like the V-Band Flange is the same diameter as the 4" body?)

#2 I have seen a few mentions of the AR DP as the "only 5" downpipe" for the N55, however x-ph.com seems to indicate it as a 4"? The CP-e is stated to be 5", I am assuming it is newer. Just confirming specs- I have a suspicion the N55 AR DP has changed since it first came out

#3 Cells- I have heard whispers of people suggesting a 300 cell downpipe, I have not actually seen any advertised with 300, only 200. Is there any chart or source that compares cell count? Only a couple even mention their cell count. Is this a universal measurement derived off cat diameter, or do the cell designs vary?

#4 Flow Testing- not seat of pants! Either by dyno or flow bench, are there any direct comparisons between the different downpipes? I would assume the size of the cat would make the biggest difference. Is there a direct correlation across all brands? Or does someone's (4", for example) flow better than other (4") DP's on the market? It is only logical to me that flanges for all of the DP's are the same, so for a catted DP the only (significant) difference between any of them that I can tell is the cat element itself.

#5 Emissions and Longevity - this one is super important to me! I live in California (insert unilateral groan from everyone NOT from California) and as we all know cats are required. I have seen mention that some are prone to fail quickly and throw CEL light (have heard ER does this). Does anyone know which catted DP's last the longest? Are there any that are known for NOT throwing codes or going bad? Are there any that are actually CA E.O. / CARB certified? (Because I haven't seen an EO on any of them) Or is there some law/exception that if they pass the OBD and sniffer it doesn't need EO stickers? The discussions over this have been vague, and CA smog laws have changed recently.

#7 ER DP for E92? I've seen people talk about the ER DP, haven't seen it for the coupe though- doesn't fit that application, or have I just missed it?

#6 Cat-Back exhaust: I am seeing 2 main types of PE systems, either dual 2.5" piping back from the DP, or a 3" converged single pipe. I am generally under the approach that if I go down to a single pipe, I don't want to split it back up again at the muffler- and by that same approach, I generally don't like the idea of the DP necking down to a single tube, then splitting to a dual outlet, just to merge back again (like on a Cobb 3" cat-back for example). For this reason I am leaning heavily towards Magnaflow (I have used them on a number of my cars and have always been pleased). The area of a 3" circle is ~7 square inches, whereas 2x 2.5" is 9.8 (and the 2x 2.25" being 7.9, almost the same as the single 3"), for that reason I would assume the Magnaflow would produce a better top end than the Cobb, with Cobb producing more torque and possibly less lag in the bottom end. Is there a clear style that the N55 seems to prefer? Or pipe diameter? No sense in having huge cat-back pipes that way out flow the DP, I want to keep everything balanced. I will explain my build below the questions, but if there are any systems out there that CLEARLY excel over the others in terms of flow and performance, I'm interested. From a sound approach, on basically every car I've ever compared I have always liked the sound of Magnaflow, and had them on my 350ci Chevy Nova and Datsun 240Z.

#6.5 - do any cat-backs maintain mid section cats? Haven't seen any but for peace of mind would definitely consider.

#7 Extra bungs? Needed?


The platform I am looking for:
2011-2013 335i Coupe, 6-speed preferably with M-Sport package (Blue, Silver, White or Black, in that preference order). Hopefully with tan seats (maybe red depending on paint).

Planned upgrades, in order of priority / install:
-ER Competition dual oil coolers
-Burger oil catch can
-Massive intercooler (unsure which brand, looking at VRSF 7.5" step race IC, open to suggestions. I want max charge cooling, willing to do light modification but nothing crazy, I'm unsure on the fit of the stepped 7.5", also looking at ETS 7", Wagner actually looks like an 8"?, ER's seems smallest of these, Active Autowerke doesn't have dimensions but looks big/tall, Cobb also seems on the smaller side out of these)
-Tune- likely Vishnu PROcede Rev3, but maybe BMS JB4- again, open if there is a clear choice for choosing one over the other (I would like the following pre-sets: an "economy" mode for absolute best mpg, a "max performance" mode which will be my usual setting, a "max performance with meth" tune when I want to turn on the system and get spunky running 33% or 50% meth, and a completely stock mode)
-Charge Pipe - these don't seem to vary too much, I just want to replace the plastic one and get that meth bung
-Cat-back, probably Magnaflow unless I find a reason not to
-Pure Stage 1 turbo and previously discussed down pipe
-Meth injection kit- probably Vishnu, I like the windshield washer conversion and onlly intend to occasionally use the car with meth activated
-Quiafe 3.42 limited slip
-Fully ducted front brakes and stainless steel lines
-Vented hood and CSL style trunk
-Larger squared wheels and tires

From the builds that I have seen online, this build while spraying meth should be able to reasonably put down 400rwhp- it would be awesome if it could hit this WITHOUT the meth, but on stock internals running 91 octane I'm thinking my max will be closer to the 375 range prior to spraying. Torque will obviously be more, which is why I am probably keeping the conservative gearing- this will be my daily driver, which I always build with "high speed touring" approach with a heavy emphasis on reliability, hence the oil coolers being the #1 thing I am going to spend money on. The purpose in upgrading the turbo is it seems the Pure Stage 1 is going to be more durable, but will also give me the boost to be able to pull hard entirely through redline without sacrificing any low end lag. It is my understanding that the Stage 2 MUST be used in conjunction with meth, and as I only want to spray occasionally and not leave it on all the time, I don't see myself ever making the leap to the Stage 2.

Thanks for any input!

good to see you have done your research. this is not going to be a comprehensive response, but I will make some pointers.

for starters, you are 100% headed to the right direction with this. I would probably go with the VRSF downpipe, but it is best if someone chimes in regarding downpipe options and what not. I am fairly certain that it is in fact 200cell, not 300.

if you plan on upgrading catback, I suggest saving your money and putting it elsewhere. you can get a good sounding, free flowing exhaust for a fraction of the price by modifying the stock catback which is well designed. all you really have to do is get rid of the stock muffler, replace with a high flow axle-back and it will sound/ flow great. if you have secondary cats in the midpipe (e90 n55 with xdrive has secondaries, RWD version did not) then i suggest you look into an f30 n55 midpipe. direct bolt on to the e90 you are looking for. looks stock, retains resonator and performs great.

all your other mods sound great. I am looking at intercooler and chargepipe in particular which is a must have for a 335i. I also recommend you look into the M performance short shifter (drastically changes gearbox feel for the better)

and oh, stick to a good 5w40 weight oil like motul, liquimoly, maybe shell rotella. this will slow oil burning (if the example you buy burns any oil) and may completely remove the need to invest in an oil catch can. good luck!

[thenewoldschool]

Thanks for the feedback!

To be honest, my main interest lies in the oil cooler / intercooler / tune / quaife limited slip. Following the rule of 80/20, this is going to net me the bulk of the benefit from my total build. (priced around $4k). I priced out everything I mentioned above (plus an Injen intake, forgot that from the list) at about $10k (before hood/trunk and wheels). Keep in mind you CAN find a decent 11-13 e92 335i in the $16-17k range, I've seen them. To me this makes the build much more appealing than the M3.

Also to be honest, I may not actually make it to the turbo upgrade if I like the tune enough. The intake, down pipe, and cat back seem to have minimal performance benefit- maybe about +20? I would only see them as essential for the turbo upgrade, but then again if the stock downpipe isn't much different than an aftermarket catted DP, I may add the Stage 1 turbo on the stock exhaust system (maybe muffler delete as recommended). The meth would just be for fun, and I do not plan on having it as an integral part of the tune.

Do you really think charge tubes are that essential? I wouldn't expect to notice any difference at all, I'm just adverse to plastic that can crack.

Is anyone walnut blasting the N55's? It sounds much more required for the N54's but wasn't sure if I should factor this in to my initial build.

I would still consider a vented hood for cooling- longevity is my main concern.

[thenewoldschool]

Also, for reference the downpipes I kind of have it narrowed down to:

CP-E 5” $1,034
AR 4” $820
VRSF 3.5” $530

Cobb 3" seems too small? Going with the largest seems like the obvious choice, but I'm worried about low-end bogging on the CP-e. I would say I like the looks of the quality of the AR the best. Still concerned about premature wearing out the cat element / CEL lights though

[mike@x-ph.com]

Originally Posted by thenewoldschool

Also, for reference the downpipes I kind of have it narrowed down to:

CP-E 5” $1,034
AR 4” $820
VRSF 3.5” $530

Cobb 3" seems too small? Going with the largest seems like the obvious choice, but I'm worried about low-end bogging on the CP-e. I would say I like the looks of the quality of the AR the best. Still concerned about premature wearing out the cat element / CEL lights though

We offer all 4 downpipes ... Best is AR, most popular is VRSF

[thenewoldschool]

Originally Posted by mike@x-ph.com

We offer all 4 downpipes ... Best is AR, most popular is VRSF

Mike, at this point I am very familiar with x-ph as it is one of my main comparison sources, you guys really do have great prices too (I checked)- the prices I have been quoting are rounded values off your website.

What makes you say AR is "best"?

Any input on intercoolers? The ones I've narrowed down to are VRSF 7.5" step race IC, ETS 7", Wagner (looks like an 8"?), Active Autowerke - my guess is the AA is going to be deemed "best" but hoping the VRSF is seen as on par.

[mike@x-ph.com]

Originally Posted by thenewoldschool

Mike, at this point I am very familiar with x-ph as it is one of my main comparison sources, you guys really do have great prices too (I checked)- the prices I have been quoting are rounded values off your website.

What makes you say AR is "best"?

Any input on intercoolers? The ones I've narrowed down to are VRSF 7.5" step race IC, ETS 7", Wagner (looks like an 8"?), Active Autowerke - my guess is the AA is going to be deemed "best" but hoping the VRSF is seen as on par.

AR finish quality and wielding are second to none. All their downpipes are made in the US per order.

Are you doing upgraded turbos on your car? If not the 7.5" VRSF might be too big

Wagner EVO 1 is 5"
Wagner EVO 2 is 6"

Active offers 2 intercoolers, sport and race.


Again it will all depend on your mods

[thenewoldschool]

For Active I think I was looking at Race, it was just over $1k. Heat soak is definitely the first issue I want to address.

At this point I am heavily considering running a Pure Stage 1 turbo on stock exhaust. By all accounts, the stock system is not very restrictive, and the Stage 1 is supposed to be a big bump for the PWG N55's (which I believe a 11-13 would have?)

Oil cooler and intercooler are the very first things I am going to do (with a tune). I guess ideally the IC I go with would be the largest I could benefit from stock, while still being able to handle the Stage 1 (I don't think I will ever go up to the Pure Stage 2 as it seems to require running constant meth, which I am unwilling to do).

If there really is significant gains at that point to go to a DP, cat-back and new intake I will, it's just been my experience that results for bolt on's are varied, and BMW designs cars really well out of the box. Sometimes they miss things- like the factory "headers" on my E39 M5. Not so awesome. It's those bang-for-your buck parts I am willing to do immediately, and then ponder over whether I want a cat-back (not a fan of loud anyways).

For the record, with the factory exhaust being over 2.25", I would go with either the 2.5" dual or the 3" single.

I did find this thread, which wasn't too positive for the AR. It is old however and somewhat supports my suspicions that they underwent a design change:

http://www.e90post.com/forums/showthread.php?t=479756

and may even run this foam filter element instead of a full intake system:

http://www.e90post.com/forums/showthread.php?t=416803

If the exhaust and intake are deemed unnecessary (not trying to squeeze every last hp out remember, it's a bang-for-your-buck approach) that really trims down the build cost. Going to call up Pure and talk to them about the turbo

[thenewoldschool]

This seems to support the notion of not changing exhaust. However, would love to see testing with the Pure Stage 1 on otherwise completely stock car

[mike@x-ph.com]

Originally Posted by thenewoldschool

For Active I think I was looking at Race, it was just over $1k. Heat soak is definitely the first issue I want to address.

At this point I am heavily considering running a Pure Stage 1 turbo on stock exhaust. By all accounts, the stock system is not very restrictive, and the Stage 1 is supposed to be a big bump for the PWG N55's (which I believe a 11-13 would have?)

Oil cooler and intercooler are the very first things I am going to do (with a tune). I guess ideally the IC I go with would be the largest I could benefit from stock, while still being able to handle the Stage 1 (I don't think I will ever go up to the Pure Stage 2 as it seems to require running constant meth, which I am unwilling to do).

If there really is significant gains at that point to go to a DP, cat-back and new intake I will, it's just been my experience that results for bolt on's are varied, and BMW designs cars really well out of the box. Sometimes they miss things- like the factory "headers" on my E39 M5. Not so awesome. It's those bang-for-your buck parts I am willing to do immediately, and then ponder over whether I want a cat-back (not a fan of loud anyways).

For the record, with the factory exhaust being over 2.25", I would go with either the 2.5" dual or the 3" single.

I did find this thread, which wasn't too positive for the AR. It is old however and somewhat supports my suspicions that they underwent a design change:

http://www.e90post.com/forums/showthread.php?t=479756

and may even run this foam filter element instead of a full intake system:

http://www.e90post.com/forums/showthread.php?t=416803

If the exhaust and intake are deemed unnecessary (not trying to squeeze every last hp out remember, it's a bang-for-your-buck approach) that really trims down the build cost. Going to call up Pure and talk to them about the turbo

If you are doing stage 1 turbo i would get Wagner EVO II or VRSF 7" high density

[thenewoldschool]

I was about to ask why not the 7.5" stepped, but I think I just answered it... it's not for N55's is it?

Would the 7" high density handle a Pure Stage 2 turbo build? Maybe 500rwhp?

I'm surprised I don't hear more people talking about diff swaps. Seeing the kind of power guys are putting down compared to 1/4 mile times, I would think there's definitely some time to be unlocked there? If I end up going with a used M3 diff I will probably get it re-geared back to 3.42 or maybe even 3.55?

[mike@x-ph.com]

Originally Posted by thenewoldschool

I was about to ask why not the 7.5" stepped, but I think I just answered it... it's not for N55's is it?

Would the 7" high density handle a Pure Stage 2 turbo build? Maybe 500rwhp?

I'm surprised I don't hear more people talking about diff swaps. Seeing the kind of power guys are putting down compared to 1/4 mile times, I would think there's definitely some time to be unlocked there? If I end up going with a used M3 diff I will probably get it re-geared back to 3.42 or maybe even 3.55?

Hi,
7.5" stepped will work on the E chassis N55 and it is a very good option for upgraded turbos.
I did not mention it because it will be too big for stock or stage 1 turbo.


7" high density can definitely handle the pure stage 2 turbo

[thenewoldschool]

Thanks Mike! I'll be going with the 7" high density.

The more I look at dyno charts it really looks like Catted aftermarket DP's don't have a significant difference but tangible gains when you go to cattless- it just also looks like a pain to swap DP's back and forth

[mike@x-ph.com]

Originally Posted by thenewoldschool

Thanks Mike! I'll be going with the 7" high density.

The more I look at dyno charts it really looks like Catted aftermarket DP's don't have a significant difference but tangible gains when you go to cattless- it just also looks like a pain to swap DP's back and forth

You wont lose any noticeable power by going catted vs catless

[STR8-6IX]

Originally Posted by thenewoldschool

Thanks for the feedback!

To be honest, my main interest lies in the oil cooler / intercooler / tune / quaife limited slip. Following the rule of 80/20, this is going to net me the bulk of the benefit from my total build. (priced around $4k). I priced out everything I mentioned above (plus an Injen intake, forgot that from the list) at about $10k (before hood/trunk and wheels). Keep in mind you CAN find a decent 11-13 e92 335i in the $16-17k range, I've seen them. To me this makes the build much more appealing than the M3.

Also to be honest, I may not actually make it to the turbo upgrade if I like the tune enough. The intake, down pipe, and cat back seem to have minimal performance benefit- maybe about +20? I would only see them as essential for the turbo upgrade, but then again if the stock downpipe isn't much different than an aftermarket catted DP, I may add the Stage 1 turbo on the stock exhaust system (maybe muffler delete as recommended). The meth would just be for fun, and I do not plan on having it as an integral part of the tune.

Do you really think charge tubes are that essential? I wouldn't expect to notice any difference at all, I'm just adverse to plastic that can crack.

Is anyone walnut blasting the N55's? It sounds much more required for the N54's but wasn't sure if I should factor this in to my initial build.

I would still consider a vented hood for cooling- longevity is my main concern.

I personally would not bother with an intake... the stock intakes BMW make are very good quality. no need to upgrade unless you plan to upgrading turbos and pushing huge amounts of boost.

the vented hood would be helpful, BMW's run hot. I suggest you look into a cowl delete (this is more a track thing, dont remember who makes it but it allows hot air to escape out the engine bay through the cowl.) I recommend you also remove your plastic engine cover and the insulation underneath, because they trap lots of heat on an engine that already runs quite hot. the intercooler is a smart upgrade and should net good performance and ideal temps. the chargepipes on these cars are shit quality plastic and I have heard that they break quite easily when driven very aggressively. If you are a more relaxed driver you should be fine, but I recommend you upgrade that as well.

for the turbo upgrade.. if you are happy with the power you get from a tune and downpipe (which should be satisfying) I would save the turbo upgrade much further down the road when the seals go bad and it starts to burn oil.

it is good to see that you care about the longevity of your motor. some stuff I mentioned here and there to keep temps down will help prolong the life of your engine gaskets. especially considering that you live in california, I suggest you stick to 5w40 oil like motul, liqui moly, perhaps shell rotella. it will keep temps down, make your engine run quieter and smoother, and rather essential if you plan on driving the car aggressively in such a warm climate. I would stay away from mobil 1 and castrol. change oil every 5000 miles if you are concerned about the longevity of the engine.

as for walnut blasting.. Probably will be less carbon build up then the n54 but I recommend you do it anyways after 60k miles.

[STR8-6IX]

Originally Posted by thenewoldschool

For Active I think I was looking at Race, it was just over $1k. Heat soak is definitely the first issue I want to address.

At this point I am heavily considering running a Pure Stage 1 turbo on stock exhaust. By all accounts, the stock system is not very restrictive, and the Stage 1 is supposed to be a big bump for the PWG N55's (which I believe a 11-13 would have?)

Oil cooler and intercooler are the very first things I am going to do (with a tune). I guess ideally the IC I go with would be the largest I could benefit from stock, while still being able to handle the Stage 1 (I don't think I will ever go up to the Pure Stage 2 as it seems to require running constant meth, which I am unwilling to do).

If there really is significant gains at that point to go to a DP, cat-back and new intake I will, it's just been my experience that results for bolt on's are varied, and BMW designs cars really well out of the box. Sometimes they miss things- like the factory "headers" on my E39 M5. Not so awesome. It's those bang-for-your buck parts I am willing to do immediately, and then ponder over whether I want a cat-back (not a fan of loud anyways).

For the record, with the factory exhaust being over 2.25", I would go with either the 2.5" dual or the 3" single.

I did find this thread, which wasn't too positive for the AR. It is old however and somewhat supports my suspicions that they underwent a design change:

http://www.e90post.com/forums/showthread.php?t=479756

and may even run this foam filter element instead of a full intake system:

http://www.e90post.com/forums/showthread.php?t=416803

If the exhaust and intake are deemed unnecessary (not trying to squeeze every last hp out remember, it's a bang-for-your-buck approach) that really trims down the build cost. Going to call up Pure and talk to them about the turbo

the stock exhaust system on the n55 (any for basically all BMW's) are very good quality. well designed, good quality piping, not restrictive at all. I suggest you get a downpipe first and then decide if you want more sound by upgrading the axle-back. this setup will be quiet and drone-free at a cruise, but quite loud when you step on it.

as for oil temps, I would try the vented hood/ cowl delete, removing the plastic engine cover, good quality 5w40 oil, intercooler etc first and then decide if you need the oil cooler or not. (you very likely may already have a factory oil cooler to start with.)