If you are gonna have the mentality that since audis are biult by the same people who built porshethen stock items must be ideal, then DONT MOD IT AT ALL

 

Larger (aftermarket) diameter exhausts allow for more flow and performance to a certain point. Anything larger than 2.75" with stock turbo wont allow for enough back pressure and cause negative results. [sm=violent053.gif](anyone who disagrees)

My milltek (2.75")videos (turn the bass up) Not MUCH louder than stock:
http://media.putfile.com/00-A4-18t-
http://media.putfile.com/00-18t-Milltek-FWD

 

why do turbo cars need backpressure ?

 

If the exhaust is too big the air will have less pressure Taking away form your PSI. Think of jets big open exhaust when they throttle up the exhaust gets smaller to get more power and create more force. Maybe not the best example but its a quick response Atleast thats what I take away from it

 

need backpressure to help with spooling theturbo-building/maintaining boost. I would need a mechanical engineering degree to explain it any better
I think that people with stock exhuast and high boost levels like with a chip or more sometimes have limp mode problems from overboost because the stock exhaust makes too much backpressure and the compressed air builds up too much in the manifold/turbo and exceedswhat boostis requested from the ecu. Especially people who are 2000+ cuz of the boost sensor in the ic. I was having overboost/limpmode problems until i got my exhaust. (remember arif?)

 

Ditto