[M2Thanh]

I know there are a lot of benefits to going with catless downpipes, but has anyone ended up regretting it for any reason? Especially Daily Drivers

Pros: sound, power, throttle response
Cons: exhaust smell, raspy tone, check engine light, running rich codes

[tpl.mallon]

No major regrets here on my G87 daily, but the exhaust smell at idle (especially cold starts and stoplights with windows down) is real and stronger than I expected. It lingers in the garage too.

The raspy tone can get annoying on longer drives if you don't add a resonated midpipe or keep secondary cats. CEL is easy to manage with O2 spacers or a tune.

Power and response are noticeably better though, and the sound is addictive in Sport mode. If you're okay with the smell and potential drone, go for it. Otherwise, high-flow catted downpipes are a safer middle ground for daily use.

What setup are you thinking?

[mike@x-ph.com]

its been a while since i last used catless, but i got tired from the smell and the raspy sound and switched to high flow catted when i need to upgrade the downpipes. never looked back

maybe im just getting older

[Info@mad-us.com]

It honestly depends on you and you alone. Give us a list of wants and do not wants and we can try and guide you in the best way possible.

Are you planning to tune in the future?

[M2Thanh]

Originally Posted by Info@mad-us.com

It honestly depends on you and you alone. Give us a list of wants and do not wants and we can try and guide you in the best way possible.

Are you planning to tune in the future?

no tune: i have non resonated midpipes with valve controller but i want more aggression. i had catted downpipes in my b58 and went back to catless because the flow seemed restrictive with catted.

im 80% sure i will go catless downpipes because i loved the set up in my b58. never heard them in a s58 though

im looking for better throttle response, more volume

[M2Thanh]

Originally Posted by tpl.mallon

No major regrets here on my G87 daily, but the exhaust smell at idle (especially cold starts and stoplights with windows down) is real and stronger than I expected. It lingers in the garage too.

The raspy tone can get annoying on longer drives if you don't add a resonated midpipe or keep secondary cats. CEL is easy to manage with O2 spacers or a tune.

Power and response are noticeably better though, and the sound is addictive in Sport mode. If you're okay with the smell and potential drone, go for it. Otherwise, high-flow catted downpipes are a safer middle ground for daily use.

What setup are you thinking?

I had a catted dp set up in my supra, and I loved it. The throttle response is so much better compared to the catted downpipe’s. just unsure how catless set up will be on an S 58
.

i’m looking at a 3.5” catless downpipe

in my supra, i went catless then catted because i thought the sound would be deeper but it wasn’t. it was sooo quiet and the throttle response was significantly less with catted downpipe, so i switched back to catless.

[M2Thanh]

Originally Posted by mike@x-ph.com

its been a while since i last used catless, but i got tired from the smell and the raspy sound and switched to high flow catted when i need to upgrade the downpipes. never looked back

maybe im just getting older

im 43 but i still enjoy that aggressive tone. thankful for the valve controller lol.

[digitldlnkwnt]

Originally Posted by M2Thanh

I know there are a lot of benefits to going with catless downpipes, but has anyone ended up regretting it for any reason? Especially Daily Drivers

Pros: sound, power, throttle response
Cons: exhaust smell, raspy tone, check engine light, running rich codes

You forgot needlessly polluting the air we breathe. I’m not a tree hugger but as a huge fan of air, I honestly can’t see why 400 cell couldn’t suffice.

And the throttle response can be tuned via CS flash or throttle mapper - power wise you’d loose like less than 10? It’s really insignificant.

The cons severely outweigh the pros.

[DrewNewM2]

I ran catless on my older STis because they made a bit more noticeable power but my current one is catted and I have Mad Catted downpipes and a single resonated mid pipe in my garage awaiting install on my G87 with plans to unlock and tune in near future. Don’t want rasp or smells and pretty sure I wouldn’t know if there was a power difference at the power levels of tuned S58.

[M2Thanh]

Originally Posted by DrewNewM2

I ran catless on my older STis because they made a bit more noticeable power but my current one is catted and I have Mad Catted downpipes and a single resonated mid pipe in my garage awaiting install on my G87 with plans to unlock and tune in near future. Don’t want rasp or smells and pretty sure I wouldn’t know if there was a power difference at the power levels of tuned S58.

it was a huge difference on my b58. i thought the same and went from catless > catted > back to catless because of how restrictive the catted downpipes still are. I could tell instantly. so much that i changed the downpipes a 3rd time lol.

[Info@mad-us.com]

Originally Posted by M2Thanh

no tune: i have non resonated midpipes with valve controller but i want more aggression. i had catted downpipes in my b58 and went back to catless because the flow seemed restrictive with catted.

im 80% sure i will go catless downpipes because i loved the set up in my b58. never heard them in a s58 though

im looking for better throttle response, more volume

Well you will get everything you are requesting and some rasp to go along with it in the mid range. As long as you are ok with that i'd say go for it.

Our fatboy downpipe would be my go to choice!

[mike@x-ph.com]

Originally Posted by M2Thanh

im 43 but i still enjoy that aggressive tone. thankful for the valve controller lol.

I im 38, and for the last 8 years, high-flow catted downpipes with a valve controller and a midpipe have been more than enough.

[M_Power Rob]

Originally Posted by mike@x-ph.com

I im 38, and for the last 8 years, high-flow catted downpipes with a valve controller and a midpipe have been more than enough.

I will be 59 next month, highflow catted downpipes and Valvetronic catback valved sport exhaust system (with pops and bangs tuned out as part of my custom tune) is just perfect for me.

[mike@x-ph.com]

Originally Posted by M_Power Rob

I will be 59 next month, highflow catted downpipes and Valvetronic catback valved sport exhaust system (with pops and bangs tuned out as part of my custom tune) is just perfect for me.

thats an excellent combo

[it.g.ma_g87]

Love driving with windows down and hate the smell, not worth no matter the power gains

[Ehloo]

the smell is something else and will
make you light headed. i tired carless in a previous AMG and ended up adding high flow cats a couple days later

if you got kids i would say no. literally posioning the air and as others mentioned it lingers.

even with 400 cel high flow cats you still smell a little of it. most high quality high flow cats flow very well and close to catless

i would go 400 cell if i ever considered it again

[marconi118]

keeping the OEM secondary cats (they are metallic) is there smell?
Meaning putting catless downpipes on stock full exhaust

[wax50]

Originally Posted by marconi118

keeping the OEM secondary cats (they are metallic) is there smell?
Meaning putting catless downpipes on stock full exhaust

No there isn’t, honestly it was a order mistake by me when I ordered everything and I had to keep the secondary cats.

I run catless downpipes, and complete turner race catback. So no midpipes or muffler.

To me it’s perfect as no smell, which I don’t care about honestly, however no smell and no rasp.

I am unlocked and able to tune out to just suttle burbles and pops here and there.

Really can’t go wrong if you just leave the secondary.

My other M I just bought a resonated catback. Same combo as other, only difference you do have some smell and at top top end of rpm range you will get suttle rasp.

[digitldlnkwnt]

Originally Posted by marconi118

keeping the OEM secondary cats (they are metallic) is there smell?
Meaning putting catless downpipes on stock full exhaust

I am curious what the advantage is here.

On the primaries you get the benefit of an open closed loop system where the DME is able to help regulate using feedback from the primary and secondary O2 sensors with the cat in the middle.
Maintaining a high quality 400 cell cat here sets the exhaust gas velocity through rest of the system until the muffler section.

The secondary cats, as far as I can tell, are just “cleaning up” a bit of left over exhaust/acting as a resonator.
They also slow down your exhaust gas column mid-stream which is less optimal.

Basically your just moving the same restriction further down stream where the exhaust gas column has already lost some velocity.

[marconi118]

just because I assume that the secondary cats have less restriction than the OEM downpipes, is this wrong?

All race cars have the cats as far as possible from the engine to gain flow and power, should'nt be any gain from catless downpipes keeping the secondary oem metallic cats?
Ideally I would move the secondary O2 sensors after the secondary cats to have correct reading and no CEL

[Info@mad-us.com]

Originally Posted by marconi118

just because I assume that the secondary cats have less restriction than the OEM downpipes, is this wrong?

All race cars have the cats as far as possible from the engine to gain flow and power, should'nt be any gain from catless downpipes keeping the secondary oem metallic cats?
Ideally I would move the secondary O2 sensors after the secondary cats to have correct reading and no CEL

You are correct secondaries are less restrictive than the primary cats in the downpipes. I believe they are 200 cell.

Do not move your secondary o2's.