I've done a search but came up empty handed. I'm running a basically stock S5 motor with stock boost etc (the wastegate has been ported to help control boost creep) but in a much lighter car.

I am currently in the 120 inch length range but could gain a lot of ground clearance and lose some weight with a much shorter exhaust system. Of course I don't want to really screw up the power characteristics.

So here's my question: using 2.5" tubing and a Racing Beat presilencer, (want to stay within track noise regulations) is there a recommendation for exhaust overall length?

I have a fair amount of flexibility, could wind up anywhere from 70" to 96" without much, if any, trouble.

 

Exhaust length tuning is only critical on NA cars. They rely on primary and secondary lengths to take full advantage of scavenging from exhaust pulses. Turbo cars like as free flowing an exhaust as possible. If you make it short, be aware that you're dumping a lot of hear via convection under the car and likely open flames.

 

Ah, okay, that explains why there is so little information about it out there; it's basically a non issue. Still learning on boosted setups!

My plan is to dump the exhaust out of the side of the car, not nuts about fireballs in the area of fuel lines, wiring etc.