Exhaust Tubing

What size exhaust tubing do you think gives you the max return on the track (take into consideration tourque and HP)

Please be sure to mention what engine/engines you would be refering to and please limit your responses to IT cars not GT cars with 4" pipes!!!

As always I am interested in what would be best on a 2.2L Audi 5cyl but hey I want others to learn as well so feel free to respond for any motor(s).

Example of what the heck I am talking about... I read on another forum that a 2.25" pipe gives better tourque than a 2.5" pipe. If this is true does it improve lap times???

Thanks;

Raymond "I wish I had a Dyno sponsor" Blethen
RST Performance Racing

How your header is tuned to your cam is more important than the tubing size. 2.25" tubing (after the collector) works pretty well for the VW's, and I don't know anyone running 2.5" tubing.

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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608

I ran a 2.25" setup.. It felt HOT out of the corners... Really nice torque.

Then I went to 2.5" and now its HOT on top.. So Just depends on your track etc.. I would say 2.5 for your size motor.. Its a good bit bigger than a CRX motor and thus could produce more exhaust thrust!