I am stumped as a GT42 is a 1000bhp turbo whatever exhaust housing used its just toooooo big for a YB and been recommended NOT to use it......instead to go for a T66 or T70 NON roller bearing..this is from a pro's mouth before you all start saying its bollocks They reckon it will spin up around 500rpm later than a T4 and be good for 700bhp...quite cheap to me aswell Anyone got any knowledge on these for a YB?