[Vinnief96]

Friend gave me his old high flow downpipe for his 340i that he sold. He had the downpipe on for around 20k miles, and I know he had burbles on hard… but the downpipe was free, so I took it! Just now inspecting it and it looks like some fins have broken off of the actual “cat” portion inside the downpipes. I’m surprised he was driving around with this connected to his turbo. I originally intended to use this on my b58… but now I am not so sure.. does this still look safe to use permitting I removed the broken bits?

[B58]

That cat is fucked up. Just gut it out.

[5w20]

Gut it out.

[Skyhigh]

It is not completely gone yet, but it has started shrinking and has progressed sufficiently. I wouldn't put it on. You risk blockage. Curious - what downpipe is that?

[mike@x-ph.com]

I would not use it

[Vinnief96]

Originally Posted by Skyhigh

It is not completely gone yet, but it has started shrinking and has progressed sufficiently. I wouldn't put it on. You risk blockage. Curious - what downpipe is that?

Can you elaborate a bit more please? Do they normally “shrink”? Blockage as in not enough flow going through the downpipe? My main worry was those metal bits being near the turbo propeller.. is that a valid concern? Or is blockage really the only concern? The downpipe is from evolution racewerks

[Vinnief96]

Originally Posted by B58

That cat is fucked up. Just gut it out.

That seems to be the common consensus.. curious if actual damaged was or can occur from this. Don’t like the raspiness of catless, but if is my only option will probably opt for it instead of dropping $900 for a brand new one

[mike@x-ph.com]

Originally Posted by Vinnief96

That seems to be the common consensus.. curious if actual damaged was or can occur from this. Don’t like the raspiness of catless, but if is my only option will probably opt for it instead of dropping $900 for a brand new one

Why $900? the MAD catted downpipe is $359 with the labor day sale.

[BMWILUVU]

Originally Posted by Vinnief96

Can you elaborate a bit more please? Do they normally “shrink”? Blockage as in not enough flow going through the downpipe? My main worry was those metal bits being near the turbo propeller.. is that a valid concern? Or is blockage really the only concern? The downpipe is from evolution racewerks

It does not look as if it will be a high flow cat anymore so I would not use it.

[Vinnief96]

Originally Posted by mike@x-ph.com

Why $900? the MAD catted downpipe is $359 with the labor day sale.

Because I have had great experience with ER not throwing codes and keeping monitors in a ready state for inspections on different engines, and that is their price. I’m sure MAD is decent, but will it keep monitors ready for inspection? 🤔 and do you think that cat would hold up any better to burbles than the ER @ half the price?? Granted I would have mine on low to medium, and not hard. I know.. “if you want burbles go catless” but I hate the rasp that comes with it.

[mike@x-ph.com]

Originally Posted by Vinnief96

Because I have had great experience with ER not throwing codes and keeping monitors in a ready state for inspections on different engines, and that is their price. I’m sure MAD is decent, but will it keep monitors ready for inspection? 🤔 and do you think that cat would hold up any better to burbles than the ER @ half the price?? Granted I would have mine on low to medium, and not hard. I know.. “if you want burbles go catless” but I hate the rasp that comes with it.

ER is twice the price because it's made in the US, its finish is second to none. If that's what you are going for, stick with ER.

Fitment, performance, sound, and reliability are the same as MAD. If these factors are more important, then MAD is the smarter buy.

Regarding the cat, they both use generic cats that will trigger the check engine light if the car is not tuned. Neither option will keep the monitors ready.
Im surprised to hear that ER did not trigger the check engine light for you, but i would not expect the new downpipe to do the same, even if it's the same brand.

[Skyhigh]

Out of curiosity mike@x-ph.com, which emission-compliant (No-CEL) catted B58 DP in the states has best reputation in terms of reliability, for the time being?

[Vinnief96]

Originally Posted by mike@x-ph.com

ER is twice the price because it's made in the US, its finish is second to none. If that's what you are going for, stick with ER.

Fitment, performance, sound, and reliability are the same as MAD. If these factors are more important, then MAD is the smarter buy.

Regarding the cat, they both use generic cats that will trigger the check engine light if the car is not tuned. Neither option will keep the monitors ready.
Im surprised to hear that ER did not trigger the check engine light for you, but i would not expect the new downpipe to do the same, even if it's the same brand.

Yeah I have had 3 different bmws each with an evolution racewerk downpipe, and each time I had NO issue passing inspection, nor did I have a check engine light for ANY of them. Makes me wonder if I’m just the luckiest sob in the downpipe department

[mike@x-ph.com]

Originally Posted by Skyhigh

Out of curiosity mike@x-ph.com, which emission-compliant (No-CEL) catted B58 DP in the states has best reputation in terms of reliability, for the time being?

Active Autowerke

Originally Posted by Vinnief96

Yeah I have had 3 different bmws each with an evolution racewerk downpipe, and each time I had NO issue passing inspection, nor did I have a check engine light for ANY of them. Makes me wonder if I’m just the luckiest sob in the downpipe department

No tune? no spacer?

[yupetc]

Any high flow DP that uses those GESI 400-cell cats will help you pass the inspection where O2 faults won't be triggered. However, smog test in california may still be an issue even with the GESI cats. Active Autowerke uses the GESI cats, and those are quite expensive.

[Vinnief96]

Originally Posted by mike@x-ph.com

No tune? no spacer?

Had a tune on 2 of them, but not the 1 so Im pretty sure it isn’t the tune auto deleting them, as if it was, the monitors would not be “ready”. But I know for a fact at the dmv, my monitors showed up on their computer as “ready “” each time, and they were each time I scanned my car.

[Skyhigh]

Originally Posted by yupetc

Any high flow DP that uses those GESI 400-cell cats will help you pass the inspection where O2 faults won't be triggered. However, smog test in california may still be an issue even with the GESI cats. Active Autowerke uses the GESI cats, and those are quite expensive.

The AA DP is 400 cell? 😳
Meaning potentially more restrictive than a HJS-catted DP?

[yupetc]

Originally Posted by Skyhigh

The AA DP is 400 cell? 😳
Meaning potentially more restrictive than a HJS-catted DP?

Yes, they are 400 cell, but they are some enlarged channels and casing body. If you go on their website and look around, the one I bought is a 400 cell GESI rated for 500-850 wheel horsepower applications. So despite the restrictivity physics talk, somehow they can pass that much air through it while efficiently treat the exhaust to qualify for O2 sniff.

[mike@x-ph.com]

Originally Posted by Skyhigh

The AA DP is 400 cell? ��
Meaning potentially more restrictive than a HJS-catted DP?

Originally Posted by yupetc

Yes, they are 400 cell, but they are some enlarged channels and casing body. If you go on their website and look around, the one I bought is a 400 cell GESI rated for 500-850 wheel horsepower applications. So despite the restrictivity physics talk, somehow they can pass that much air through it while efficiently treat the exhaust to qualify for O2 sniff.

+1

A higher CEL doesn't automatically equate to reduced power; it's more about the quality of the catalytic converters. For instance, GESI cats are rated for up to 850 HP so you won't see any power loss with a stock turbo setup.

If you upgrade your turbo, catless get you an extra 20 HP over high-flow catted.

In my opinion, the benefits of no smell and no CEL make up for the minor 20 HP difference; and that's only if you've upgraded your turbo.

[Skyhigh]

Fully agree. Was just surprised to read it is more than 300 cell nevertheless. Hopefully more robust than the 300 HJS cats which have started to fail (detach and shrink) in various downpipes 😐Often due to heavy burbles and gunshots, but not only.

[yupetc]

Originally Posted by Skyhigh

Fully agree. Was just surprised to read it is more than 300 cell nevertheless. Hopefully more robust than the 300 HJS cats which have started to fail (detach and shrink) in various downpipes 😐Often due to heavy burbles and gunshots, but not only.

I run the GESI cats in my custom hi-flow dp without any issues for 5 months now. Been beaten my N55 motor every chance I get. That cat is solid and no smelly exhaust anymore.

I did run this GESI cat with MHD tune and optioned it for catless dp for a month and catted dp for a month, all of which resulted in no O2 circuit fault. Now I just simply leave it at catless dp in the option menu and call it good.

Now I get to pull up at my annual inspections without worrying about them questioning the strong CO2 smell because there's practically none present.

Currently running MHD stage 2+

[Skyhigh]

I am running a HJS cat in an Akrapovic DP, which is fantastic. 2 years now. No complains. No CEL. But I have not inspected it.