Thats some funny ass GT28RS people have if they think it will even get 400, never mind 450



Id say something like a GT3071R at mega boost, 2.5bar (thats still on the compressor map on that turbo) or summat (for maximum torque and so you dont need a too big turbo, like T4), as high comp as you can get away with at that sorta boost (8:1? 7.5? TBH it dont make much odds in reality), lowest duration cams you can get away with (standard? i dunno), mildly ported head, not big ports, just make it all better, etc etc.

Basically keep everything as small and as big boost as possible for the power you want, for maximum torque and response.