Currently I have a 60mm trust exhaust with a 2.5" down pipe with no cat. I was wondering if going to a 3" exhaust and down pipe with a 3" carsound cat would gain or lose horsepower seeing as a cat would restrict exhaust flow? This is for a t3/t4 turbo b18c.

thanks,
Brad

 

the 3inch exhaust with 3inch dp and car sound cat should give you the extra hp. it all depends on if you run low or high boost. tooo

 

would the 3" set up be good for 8-9 psi, or would that be on the low side?

thanks.

 

low side but still would yield gains. Turbos like a non restrictive exhaust. the freer the flow the more hp and the faster it will spool up.