Im not sure how big my stock pipe is, but does it rob horsepower like the stock exhaust manifolds and y-pipe do? Im thinking of getting the Hooker Cat-Back replacing my flowmaster 80. Does this bolt directly onto the stock cat? Also, Ive heard the hooker cat-back on many 350s but I havent heard one off of a 305 yet, anyone have a clip of theirs? Would your sound and loudness depend on your compression as well? Mine is 9.6:1

hard to say if you don't tell us which thirdgen you have. 350 TPI has 2-3/4", 305 TPI and the better carbed 305s have 2.5", 305 TBI's have 2.25"

my 305 had was about 2 7/8th's.