Do you want 500whp on pump gas or race gas? The GT30R is pretty maxed out at 500whp the GT35R will get you damn close to your goal on pump gas, then leaving good amount of room to improve on race gas or a 50/50 mix of 93 and 100 octane, also is this going to be daily driver? also what kind of power band are you looking for? Ive been looking into building a 450+whp on pump gas in the future once money allowes. So it would be nice to see what you might have in the works.