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rxer311
01-16-2010, 06:15 PM
I was just reading another thread about a "chipped" car and it got me thinking about the exhaust of the car. I am still very new to Audi and the Audi tuning community so bear with me.

The last build I did was a 2007 STi and one thing was clear. A catback exhaust would net you 0 hp with no other modifications. When you opened up your downpipe, that was where your power was gained. The downpipe was simply the most restrictive part of the exhaust system so adding a catback exhaust was pointless. In fact many people would use a "stealthback exhaust" which was the downpipe utilizing the stock exhaust. This proved to be effective until HP numbers would get very high. Really the only need for a catback on a Subaru was because the sound of the flat 4 motor was just dead sexy.

So my question is whether a catback on our Audi 2.0t is restrictive. Are there gains with a catback exhaust on these cars or is it negligable? Is it just a noisemaker or are there actual performance gains with an exhaust?

On a different note I was actually thinking about a design for a custom catback exhaust. Basically the stock exh is 2.5" piping correct?

My design would be 2.5" piping comming off the catpipe and running to where the middle resonator muffler is now. In this space I would run a Magnaflow muffler 2.5" in and dual 2.25" out and run the pipes to the rear bumper with quad tips. One muffler would save weight and magnaflow mufflers are usually pretty quiet. Thoughts on this as well?

MCT9891
01-16-2010, 06:18 PM
If you want real power you should go with a HFC or test pipe.

but to answer ur question, if you go with awe, apr etc... no, its not just a noise maker, there are some gains.

rxer311
01-16-2010, 06:25 PM
If you want real power you should go with a HFC or test pipe.

but to answer ur question, if you go with awe, apr etc... no, its not just a noise maker, there are some gains.

I completely understand where you are comming from. I know huge gains will be made with a HFC and more with a TP. But to some of us warranty is a concern. I have a CPO car so I have 2.5 years of warranty or 70000 miles left and I got this car to be a reliable daily driver.

My dealership can provide me with the GIAC flash and maintain my warranty. Because of my subaru background I was just wondering if a Catback exhaust would actually make a difference in power. Also, I just want some sweet looking quad tips [cool] and was thinking the custom route would be a great way to acheive that.

Subaru71
01-16-2010, 06:28 PM
I completely understand where you are comming from. I know huge gains will be made with a HFC and more with a TP. But to some of us warranty is a concern. I have a CPO car so I have 2.5 years of warranty or 70000 miles left and I got this car to be a reliable daily driver.

My dealership can provide me with the GIAC flash and maintain my warranty. Because of my subaru background I was just wondering if a Catback exhaust would actually make a difference in power. Also, I just want some sweet looking quad tips [cool] and was thinking the custom route would be a great way to acheive that.

Well, a HFC and a TP is the equivalent to swapping out the DP in Subaru's..

so if you want to not take off the cat, there's not a WHOLE lot of power to be gained.

rxer311
01-16-2010, 06:34 PM
When we are talking not a whole lot of power are we talking 1-2 HP or are we talking 10-12 HP? 10 HP on these cars would be significant at a 5% gain.

Do you think my design for a custom exhaust is doable or would a more conventional design with 2 mufflers at the outlets would be a better overall design. My thought is 1 muffler is less restrictive than 2.

Nikoman
01-16-2010, 06:43 PM
Dude, HFC or exhasust won't void your warranty. GO with HFC first for sure. I've had mine for a while and zero issues at the dealer. Got my APR exhasut later and i noticed almost no gains but the sound is [up]

rxer311
01-16-2010, 06:44 PM
Dude, HFC or exhasust won't void your warranty. GO with HFC first for sure. I've had mine for a while and zero issues at the dealer. Got my APR exhasut later and i noticed almost no gains but the sound is [up]

In talking to my service manager (he lives 2 doors down from me) a GIAC flash or a catback will not affect the warranty, but, depending on what goes wrong, a test pipe or HFC can.

Nikoman
01-16-2010, 08:24 PM
Ya, maybe an 02 sensor, that's about it. It's worth the risk or cost out of pocket for the 02 sensor imo.

rxer311
01-16-2010, 08:43 PM
Ya, maybe an 02 sensor, that's about it. It's worth the risk or cost out of pocket for the 02 sensor imo.

Or a cracked ringland and a whole engine rebuild...

a3s-line
01-17-2010, 01:06 PM
Is it correct to delete the centre muffler (after the cat) and replace the back mufflers with something more free flow and a bit bigger in diameter? Any gains from that?

rxer311
01-17-2010, 02:26 PM
Is it correct to delete the centre muffler (after the cat) and replace the back mufflers with something more free flow and a bit bigger in diameter? Any gains from that?

Yes, basically replace the resonators with a muffler and then just run straight pipes back from that and run quad tips. I would think a single muffler would save weight and have less resistance. That is what I am trying to find out.

rxer311
01-17-2010, 06:13 PM
Yes, basically replace the resonators with a muffler and then just run straight pipes back from that and run quad tips. I would think a single muffler would save weight and have less resistance. That is what I am trying to find out.

So does anybody have thoughts on this?