Don't the vette have true duals from the factory? I can't remember which year the vette went to one in and one out. In any event I'd make your self some true duals..well sorta anyway. Get headers, as long as you can get, some 3" pipe, two high flow cats, some more pipe, and a flowmaster 80 series muffler get the one with 2 in and 2 out. There's a guy at work that has this set up..add that with the LS6 intake, pollished heads..don't really need to port them, larger valves, cam, throttle body and mass airflow senser I think you'll be pretty close to your mark.