Exhaust Performance Gains

[Hamsteak]

Hello Everyone!

Recently i've been curious about how much power gains I would get out of an aftermarket exhaust. A lot of companies don't give hp numbers and the ones that do like IE (8-12 whp downpipe) or ECS (full catback 19whp) peaked my interest.

I'm, currently above Dual Pulley stage 2 with an IE throttle body and Ported Supercharger and think that these systems could really benefit the car! However, I'd like to see what others think before I dive into such a pricey purchase. Is there a noticeable power increase when driving? What systems would you recommend? I'd love some input!

[Ashtonts]

The fastest cars on this platform have usually used modified stock exhausts. You probably won't see much if any gain from going aftermarket. That said I love my AWE setup

[BEight SFour]

AWE sound > 10-19HP

Sent from my SM-G975U using Audizine Forum mobile app (http://r.tapatalk.com/byo?rid=87676)

[djn876]

I just spent some time looking at this recently, if it is like the SQ5, you probably have a 2.25" exhaust (nominal) from the factory, this will likely support even a dual pulley 93 tune without much restriction, if you start running an e40 tune, where you are going to be pushing in the 550 - 600 range, a 2.5" exhaust and likely at least a high flow cat would probably be beneficial to remove some of the restriction, thereby improving engine efficiency. How that translates to actual numbers whether it is 5 or 30 hp I couldn't tell you.

[doughboy17]

The fastest cars on this platform have usually used modified stock exhausts. You probably won't see much if any gain from going aftermarket. That said I love my AWE setup


AWE sound > 10-19HP

Sent from my SM-G975U using Audizine Forum mobile app (http://r.tapatalk.com/byo?rid=87676)

This ^

[04lss]

Personally, id look more into headers and high flow cats rather than downpipes and the mufflers. Swapping exhaust manifolds to headers and the cats to high flow will probably net a fair bit more flow for you than replacing your mufflers or downipes. just my.02

[usmcfieldmp]

Matty's car that ran a 10.2@134 was running stock downpipes and catback.

I noticed zero butt-dyno difference when I switched to the Polo cat-back. The sound is the real/only benefit to an exhaust on these cars, imo.

[Hamsteak]

Thanks for all the replies everyone!

I'll definitely refer to this thread if I end up doing more exhaust work in the future, regardless of response I had planned ahead of time to get my cats gutted this coming Monday, due to the fact my area of Georgia has no emission laws/regulations.

To my understanding from what I'm reading, downpipes and catbacks don't serve as much as a performance gain but rather being just for sound (unless I run more aggressive fuels), while gutting cats and test pipes/headers serve to increase power. I was almost worried I'd been missing out on a huge power gain were I not to install an aftermarket exhaust on my s4 but it would seem that all that worry was for nothing.

[MrFunk]

You may notice improved throttle response - slight improvement. Any increase in power is probably so high in the RPM range that it's negligible.
With that being said - I think an exhaust upgrade (AWE specifically) is the best and most satisfying upgrade I've done. The sound of the car stock is meh, but with an AWE exhaust it's intoxicating... really transforms the driving experience into really feeling like you're driving something special. Not sure why they muted the stock exhaust so much but thank goodness for the aftermarket!

[04lss]

Thanks for all the replies everyone!

I'll definitely refer to this thread if I end up doing more exhaust work in the future, regardless of response I had planned ahead of time to get my cats gutted this coming Monday, due to the fact my area of Georgia has no emission laws/regulations.

To my understanding from what I'm reading, downpipes and catbacks don't serve as much as a performance gain but rather being just for sound (unless I run more aggressive fuels), while gutting cats and test pipes/headers serve to increase power. I was almost worried I'd been missing out on a huge power gain were I not to install an aftermarket exhaust on my s4 but it would seem that all that worry was for nothing.

On a lot of cars downpipe upgrades net power, but its becuase thats where the Cats usually are. I was surprised to find out the cats were somewhere else on these cars. Especially on turbo applications cats help because of turbo spool.
I upgraded the downpipe on my old 3800 SC car, and the factory downpipe has a dip in it for the o2 sensor thats particularly bad about exhaust flow. Still didnt make that much of a difference. But youre at the point of 5-10 horspower mods here and there it seems. Now something to consider is weight savings. if you can reduce the weight of your exhaust you might gain something, but again probably nothing major. I know on my mustang removing the resonator was worth like 20lbs.

- - - Updated - - -

I think of a catback the same way i thought of my IE intake on my GTI. Doesnt really serve a performance purpose, but the noises make me happy.

[usmcfieldmp]

Thanks for all the replies everyone!

I'll definitely refer to this thread if I end up doing more exhaust work in the future, regardless of response I had planned ahead of time to get my cats gutted this coming Monday, due to the fact my area of Georgia has no emission laws/regulations.

To my understanding from what I'm reading, downpipes and catbacks don't serve as much as a performance gain but rather being just for sound (unless I run more aggressive fuels), while gutting cats and test pipes/headers serve to increase power. I was almost worried I'd been missing out on a huge power gain were I not to install an aftermarket exhaust on my s4 but it would seem that all that worry was for nothing.

Cats for these cars can be worth a very decent chunk of change... and replacing them is very expensive. I never recommend the gutting route.


I think an exhaust upgrade (AWE specifically) is the best and most satisfying upgrade I've done. The sound of the car stock is meh, but with an AWE exhaust it's intoxicating... really transforms the driving experience into really feeling like you're driving something special. Not sure why they muted the stock exhaust so much but thank goodness for the aftermarket!

I agree with this 100%. I love driving the car so much more with an exhaust on it. Especially hard DSG upshifts and downshifts.

[Hamsteak]

Cats for these cars can be worth a very decent chunk of change... and replacing them is very expensive. I never recommend the gutting route.

If worst comes to worst ill just buy some test pipes down the line and get them installed, I know a good shop down here and I get a bit of a discount for the work they do. Doesn't make it NOT expensive to get it installed though.

[04lss]

If worst comes to worst ill just buy some test pipes down the line and get them installed, I know a good shop down here and I get a bit of a discount for the work they do. Doesn't make it NOT expensive to get it installed though.

I read 10 hours labor with the DSG [o_o] Its why even though i have some issues with my DP flex pipe, im not planning to do any exhaust work until i see how well the cats hold. JHM makes a trick kit that moves the cats down into the downpipe section of the exhaust and you replace the factory stuff with test pipes.

[Hamsteak]

I read 10 hours labor with the DSG [o_o] Its why even though i have some issues with my DP flex pipe, im not planning to do any exhaust work until i see how well the cats hold. JHM makes a trick kit that moves the cats down into the downpipe section of the exhaust and you replace the factory stuff with test pipes.

Boosted Dynamic Tuning made a great video on how to install testpipes without completely dropping the subframe, making it a shorter install. I sent it to the guys that are going to do it and said it would probably be less than 10 hours.

I also saw the JHM kit which I thought was pretty interesting but wont need for the time being, I'm just going to run catless and if need be that kit would probably be the 2nd best option.