Are you keeping the existing AFM in a suck through mode? How are you going to handle detonation? Do you have some sort of knock sensor that will retard timing? I can't wait to see the pics of how all this fits in the engine compartment, sounds extremely tight.
Ummm... Sequential turbos, 300+hp is conservative when you consider that the Supra was 300+ with smaller turbos and a 17% smaller capacity engine...