A standard T34.63 is at its limits running near 400bhp on pump fuel. Rainbird ran one decades ago at that power but it was on better fuel than we have these days.

sure it will do 400bhp but youll be running it at its limit of boost and it wont last forever.

The concensus on here the last few times this 400bhp question was asked was that the figure of 400bhp is a bit odd in tuning terms and its far easier to spec for 380bhp or jump to 430bhp plus.