55s t34.63 should be 400bhp with the right cams. If your pistons have cutouts get some bd14s and 16s go for a l8 ecu (u can have launch controll anti lagg if u got right turbo closed loop etc etc)a new inlet will prob help u out at that power range. There's a group buy going on at mo so get a bargain.

Only prob with above spec is gearbox has to be decent and you'l defo need a new clutch and prob a diff. Thats why people say it starts to get expensive over 380