before i put the turbo engine in my 77 i gutted the cat,put new injectors and injector connectors on.rebuilt a distributor with a better advance curve.ran 2.5' exhaust behind the cat.car ran very well-out drag raced a 94 camaro z28 with auto trans.remember to start with the basics before buying aftermarkit parts.back in the day these cars were made the gasoline didnt have injector cleaner in it-so the chances of your car having injectors flowing 60% to 90% of total flow are good.a megasquirt system with new injectors,a mild cam and good exhaust would make these cars run well.