well im in the proccess of building my na to turbo it so far has plazaman 1000hp intercooler, plazaman hot side and cold side, plazaman plenum, fpv f6 bf mk2 brand new motor with head done port n polish with larger valves, gt3540 turbo, atomic oil pump, surge tank borch 044, clutch and 80 pound injectors so I think that's around the 400 kw mark so you reakon twin 3 in is to big and will lose velocity or will twin 2.5 get me to roughly 400kw mark