i have a 85 firebird 305 4bbl, i want to put a cutout on it but im not sure what diameter the exhaust is its eather 2 1/2 or 2 1/4 im not sure. also where should i mount the cutout. i would think before the cat it would be real raspy and not sound good but i don't know. or after the cat. but where after the cat i would like to know if you guys could help me out on that. i have 80 series flowmasters and there not even loud. i really like the sound of the 305 in the exhaust clips at the top of the fourm in exhaust he just has a cutout where is his mounted there is a video there also. i want mine to sound like that.