Exhaust Gains... Worth the $$$?

[GRUMPY-S4]

I am pretty content with the stock exhaust. But I have two questions:

1) Is upgrading the full exhaust proven to give any significant gains? Or are the gains mostly the downpipes swap or not even that?

2) Has anyone done custom tips on our stock exhaust?


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[jokingjimmy]

I was wondering about axle back or muffler delete, so subbed.

[GRUMPY-S4]

Whats an Axle back? Cat Back?


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[Pyromatic177]

Axle Back is replacing the mufflers/removing them. Buddy of mine removed the mufflers. So it's just center res like the AWE Track Exhaust. It's pretty loud. But he much prefers my Borla System over what he did.

[GRUMPY-S4]

If you want just sound... Then catback or replace mufflers.

If you want performance then just Downpipes... But I wonder how much is the gain vs the cost???


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[Pyromatic177]

The DP's add sound as well. Different tone. I have non Res Downpipes.
And guys don't do it for gains. Not when, for the same price you can go Stage 1

[GRUMPY-S4]

I met with TexasDfwS4 today and discussed this and he was saying how the exhaust mods on this car are not worth the investment if you have your mindset on power gains. Mostly sound. I would think the DPs would add power though??? But I guess in Resonated form they arent much better than stock in terms of flow?


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[4RingRook]

Exhaust will net you minimal performance gains (8hp at the crank). Companies like AWE offer a larger diameter pipe for better airflow which is where that gain comes from along with a better exhaust note. The improved sound is the primary reason people upgrade. I personally have the OEM downpipes with the AWE Touring exhaust and am very happy with the setup. Downpipes are for even more sound enhancement and not performance.

[14S4GWM]

I met with TexasDfwS4 today and discussed this and he was saying how the exhaust mods on this car are not worth the investment if you have your mindset on power gains. Mostly sound. I would think the DPs would add power though??? But I guess in Resonated form they arent much better than stock in terms of flow?


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Tons of threads on this topic Grumpy

[GRUMPY-S4]

8hp at crank... For $2500 plus install? That is not worth it in my book. I may then go with putting tips on the stock exhaust. Anyone done that?


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[blingaling]

I find it very very hard to believe that downpipes are just for sound and net you very minimal gains. Cats are extremely restrictive, getting those removed alone has to have some decent power gains. If i had the money id get downpipes and dyno before and after results but just purchasing stage 2 i gotta let my bank account recover a little lol


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[onlyaudis]

I find it very very hard to believe that downpipes are just for sound and net you very minimal gains. Cats are extremely restrictive, getting those removed alone has to have some decent power gains. If i had the money id get downpipes and dyno before and after results but just purchasing stage 2 i gotta let my bank account recover a little lol


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If you search, you should be able to find some dyno numbers that confirm that exhaust swaps give little power gains on these cars. believe it or not, you can make a ton a power on a good stock exhaust, with cats and all. Look at the Dodge Hellcat. it was different like 10 years ago with a more moderate performance car to start with, like a B6 or B7 A4. HFC and downpipe with a stage 1 or 2 car was a huge performance gain.

[moophone]

Not true, the downpipes are the only part that nets any real gains (15-30hp depending on which ones)

cat-back you are looking at less than 10hp, folks do it for the sound.

Exhaust will net you minimal performance gains (8hp at the crank). Companies like AWE offer a larger diameter pipe for better airflow which is where that gain comes from along with a better exhaust note. The improved sound is the primary reason people upgrade. I personally have the OEM downpipes with the AWE Touring exhaust and am very happy with the setup. Downpipes are for even more sound enhancement and not performance.

[colby7]

There's a difference between cats and downpipes. Cats are upstream of the downpipes. Manifolds, then cats, then downpipes. I believe that's the order of the pieces from the engine. The biggest power gain is in the removal of the cats either through headers or test pipes, both of which would then connect to downpipes.

[4RingRook]

Not true, the downpipes are the only part that nets any real gains (15-30hp depending on which ones)

cat-back you are looking at less than 10hp, folks do it for the sound.

Cats for performance, not downpipes.

[GRUMPY-S4]

You see why I created this thread... Seems there are different opinions. Common logic would tell you that downpipes would net hood gains. Many people here have stated that it doesnt in this car as the stock dp and exhaust are very free flowing. Others state you can make 20-30hp on a DP swap. Is that claim assuming you go catless and no resonators?


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[will13k7]

for the newbies to this platform:

this topic and been beaten to death, there are no appreciable gains by messing with any part of the exhaust path on this car, including headers, cat, dp, and back. some googling on this site and audi revolution dot net reveals all the threads on this.

[colby7]

for the newbies to this platform:

this topic and been beaten to death, there are no appreciable gains by messing with any part of the exhaust path on this car, including headers, cat, dp, and back. some googling on this site and audi revolution dot net revels all the threads on this.

All of the fastest guys have removed their OEM cats. They removed them for the hp/torque gains that are realized by removing the restriction in flow caused by cats.

[GT-R & S4]

8hp at crank... For $2500 plus install? That is not worth it in my book. I may then go with putting tips on the stock exhaust. Anyone done that?


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I felt the same way you did about the cost of the after market exhaust, compared to performance gains. I went with an AWE Touring Exhaust, with resonated downpipes, and 102mm black diamond tips. I absolutely LOVE the sound of my Stage II S4 now. It actually sounds like a performance car now, but without being annoyingly loud, or droney, I also love the whine of the supercharger after I also installed the CAI's and pulled the fuse on the fake engine sound maker. Bottom line, a new exhaust with or without CAI's, is an expensive proposition, but I'm more than satisfied with the results. Yes, you can remain stock and as many have pointed out, you're not going to miss out on that much of a boost in performance. But you could have also chosen a more pedestrian type of vehicle than an S4, but you didn't. There are many things people change on their S4's to either increase performance, or enhance the appearance. To me, that's all about making my S4 unique, and just how I want it to look, sound, and perform.

[b8audis4]

I will keep this short and sweet. Don't buy an exhaust on this car for performance gains. I bought my AWE 90mm Resonated touring exhaust due to the amazing sound. Probably the best thing I have done to it along with BBS CHR's with PSS.

[GRUMPY-S4]

My concern with the exhaust sound is interior refinement. Does it change the interior sound?


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[TexasDfwS4]

Pull the fuse and replace the exhaust with a mild system and its a wash.

[mavz]

You see why I created this thread... Seems there are different opinions. Common logic would tell you that downpipes would net hood gains. Many people here have stated that it doesnt in this car as the stock dp and exhaust are very free flowing. Others state you can make 20-30hp on a DP swap. Is that claim assuming you go catless and no resonators?


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If you want to see 20-30+ hp gain, you remove the primary cats as most people here have stated. If you want sound, you remove/change anything past that: downpipes (secondary cats) or cat-back.

[mavz]

My concern with the exhaust sound is interior refinement. Does it change the interior sound?


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You can definitely hear it more and it does sound nice. However for me (AWE tourning), it does drone which is unfortunate but comes with the territory. You can get resonated downpipes to supposedly alleviate it some more but everyone's sensitivity is different so you should sample it first hand.

[GRUMPY-S4]

But pulling the cats means possibly droning? Means issues passing emissions?


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[cspcrx]

It comes down to what do you really want.

1) Sound, looks and some, all be it very small gain in hp then spend the money on a full cat back exhaust and enjoy the sounds.

Or

2) more hp and torque out of the exhaust system with the least money spent and no worries abot sound and looks. Pull the cats and get test pipes. Several treads by some of the quickes S4s here seem to show that is where the extra power is. Equal to or more than super high dollar headers and full exhaust systems.

All of this being said if you want ever last ounce of power do all the above.

[StevenStarke]

30hp from exhaust? LOL. People must be on crack. I just put non res downpipes with the AWE touring and felt no difference. This is on top of a previous installed chipwerke pro and Roc Euro intake. MAYBE 10hp increase from DP's and exhaust.

[mavz]

But pulling the cats means possibly droning? Means issues passing emissions?


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if you pull the primary cats you aren't passing emissions... not even close lol. idk what catless is like on this car but typically you can smell a car thats catless from a few cars away. it stinks

[garynagra]

I can't speak of the hp but you will definitely gain some smiles when you smash the gas

[will13k7]

All of the fastest guys have removed their OEM cats. They removed them for the hp/torque gains that are realized by removing the restriction in flow caused by cats.

auditude4.2 is right there with primetime, he has oem cats. Jones is catless and has headers, he's behind auditude4.2 and primetime. primetime has highflow cats. there's really not much between these guys (relatively speaking), now translate that to daily driving, your butt dyno won't notice the difference.

maybe there's more to see with stage3? time will tell.

[jokingjimmy]

Axle Back is replacing the mufflers/removing them. Buddy of mine removed the mufflers. So it's just center res like the AWE Track Exhaust. It's pretty loud. But he much prefers my Borla System over what he did.

Any chance you could talk him into posting a video of the sound? I'm considering the delete, buy have very few references to see if I like it. Would be helpful and appreciated

[mrmomo313]

All of the fastest guys have removed their OEM cats. They removed them for the hp/torque gains that are realized by removing the restriction in flow caused by cats.

Well not everyone. Auditude and madman4you, both stock cat. Bunch of others in the 11s on stock cats as well. The real power adder for this platform is tune/pulley and open element intake, that alone will net 11.x race gas passes.

We also know the eurocode headers don't do anything for stage 2 cars either. Just search around. Will provided a great resource

I've seen one independent dyno test showing a gain of 18whp with the addition of the 034 pipes. They don't do much in terms of power from my testing but after hearing apr's race car, I had to have them. Def not for the faint of heart

[wwhan]

The catback exhaust does not add any power, but can produce a nice sound during accelleration (makes it easier to shift by engine sound).

The Cat removal with an 034 test pipe, makes the exhaust sound pretty raspy, especially with the APR catback. Adding a Milltek full resonated exhaust helps cut the raspy sound of the engine without Cats.

Playing with the exhaust does not add any cost effective power. Stage 2 ECU tune with pulley (& maybe intake) is the best power adder.

[moophone]

Yes this is what I meant (nobody is going to buy an aftermarket downpipe with stock cats). High flow or no cats.

Cats for performance, not downpipes.

[moophone]

Merry xmas all!

Eurotek Cat delete pipes. 28whp, 9wtq. and yes they are pricey for what they are.

From their website: "Mods at the time on the S4 included APR stage 2+ software (Version 1.1), APR supercharger pulley, Milltek resonated catback exhaust system, Carbonio stage 1 & 2 intake system and APR CPS system. All of these mods were already installed at the time of the baseline runs as well as all the runs following the installation and testing of these pipes."

I will be installing these over the holidays, first with stock exhaust. I have no idea if they will live up to the claims, but I'll report back. I also have APR TCU tune, so it will be interesting to see what happens from 6400 (where this dyno stops) up to 7400rpm. I'm worried about the smell is all, but we'll see.

30hp from exhaust? LOL. People must be on crack. I just put non res downpipes with the AWE touring and felt no difference. This is on top of a previous installed chipwerke pro and Roc Euro intake. MAYBE 10hp increase from DP's and exhaust.

[4RingRook]

Yes this is what I meant (nobody is going to buy an aftermarket downpipe with stock cats). High flow or no cats.

I see you're going catless but you are firmly in the minority. Most don't touch that component of their exhausts on the 3.0T.

[GRUMPY-S4]

I went catless on my previous car... Never again!!! The smell just ruined the car as a daily driver


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[moophone]

So what you are telling me is the trick is to just go really fast and not stop? ;) I'm very worried about doing this, but I have to see for myself.

I went catless on my previous car... Never again!!! The smell just ruined the car as a daily driver


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[GRUMPY-S4]

Keep windows up at stop lights lol


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[andthen]

I went catless on my previous car... Never again!!! The smell just ruined the car as a daily driver


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Run enthanol. Then it's smells like cattle feed.. lol


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