I am running greys with 408 bhp and 407lb of torque at the wheels so must be near 450 at the flywheel. I was also told the the old standard type exhaust was limiting me and choking it at revs. I've since changed it to a mongoose and the difference is quite noticeable.

My engine is much the same spec but with BD14 and 15 cams and a well ported head. I've also got a wrc head gasket and long studs etc.

Its crap at low speed but when the turbo (T4 on an rs500) comes in you'd better hang on tight!! Great fun ;-0