Well the truth is a stock 5.0 on an engine dyno wont throw down 225 hp. They will probably knock down 240 or so. Factor in a good intake and carb (dumping the stock TB, intake, MAF and air silencer) and I could see 53 hp over what it was RATED at. Rated vs real world are two different realities. A 278 flywheel hp car will probably throw down 220-230 at the wheels tops, and thats right where a good deal of Intake and exhaust cars are!