Best Way to reach 500 hp ,, Cheap !

Prine is LOL'd due to where the 500 hp is being measured.

Your Magnum create engine can handle a N02 of a 125 HP shot.

IF the bottle isn't OK with you, then I'd charge the engine. I myself would do a SuperCharger rather than a turbo just for the quick and easier way of charging the engine. You would only need about 6 psi.