A 0.63 a/r T34 is not really even a 400bhp turbo (it's just people push them WAY outside their compressor maps and can just about achieve this on a good engine). So a 0.55 a/r equipped one won;t just be on it's knees, it will be pleading for mercy at 400bhp . I can assure you it WILL go pop in a short while running the boost necessary to achieve this power, but if TT say it's a 400bhp turbo, I'd be interested at what they say is the cause of the failure when you send it back .