i think you'd be hard pushed to get 400hp out of t34.55 with a standard head

dont get me wrong; you could probably make 400hp; but how long the turbo will last is a different matter - i suspect you'd be ringing the turbo's neck to get that power

mine used to be a t34.55 on a standard head and i was at around 365-370hp - it makes for an awesome road car

why do you want 400? dont chase numbers; i'd rather have a car with 370hp and it drive nice compared to a 400hp car that drove horrible