I have a 1994 Pontiac Firebird Formula. I had problems with my catalytic converter a few months ago. I did not not put a cat back on my car. I had the cat cut off and replaced with a 2.5 in staight pipe. My car has stock exhaust manifolds with a 2.75 Borla Y pipe welded to the 2.5 straight pipe then welded on the stock 2.75 intermediate pipe then 2.75 mandrel bent tailpipes. I would like to know if the 2.5 straight pipe in place of the cat is a big restriction or would a 3 in pipe be alot better for flow. The piece of pipe is only about 2 foot long. Also, is my exhaust set up free flowing or a big restriction. My car is mostly stock except for Hooker Aerochamber muffler, SLP Cai, TPis airfoil, throttle body coolant bypass, cat converter removal, and the 2 3/4 Borla Y pipe.

 

I'd say its no big deal unless you have headers, which you dont.......

 

not for your setup its not