I call BS on their part. Each one uses the same rotor assembly, thus flows the same amount of air. What you dont see on the Edelbrock site is the air/fuel ratio. Even their dyno chart doesnt show if its flywheel or wheel hp. More than likely its flywheel, with that said, yes you could pull a few more horses with a more aggressive tune. Not saying Edelbrock doesn't make good stuff, its just that theirs is nothing revolutionary. Its a been there done that thing. Why Roush and Saleen are almost always the first for the Mustang is they are working hand in hand with Ford. Shoot the Roush little M90 roots blower (its been around forever) produces 445 flywheel hp. Remeber boost is a restriction, so don't just rely on that number for hp figures.