what do you guys think about using a test pipe over a cat any gains in power?

 

2.5" test pipe vs 2.5" high flow cat doesn't make a big difference. Dunno about testpipe versas OEM cat though.

 

I've heard you get more out of a test pipe...but it's not street legal, and it's louder.

 

I would guess that the test pipe on a stock R would make one a couple ponies, although they're ILLEGAL and there are some really good high flow cats out there. Also, does anyone know if carsound makes a high flow cat that would hook up to the stock R header and exhaust? It would have to be a 2" inlet and 2.25 outlet.