hey..wassup man..yea i have a 77 with da same engine. i bought some hooker headers and a pypes 2.5 inch x pipe system with v force mufflers and chrome tips. I have never been happeir with da sound it make, and i tell u u'll feel and hear da difference when u step on it, those rice boyz will just roll up their windows and turn on da enxt light...ask me how i know
. On ur question on a 3 or 2.5 inch system just know dat a 500hp car would benefit more from a 3 inch than a 2.5. Also i would go with the hyperflex system from energy suspension, polyuthren kicks A$$! good luck and have fun with the car, i know u do with mine
