Do you want to just make it or make it reliably? To just make it, induction, intercooler/pipework, injectors, valve springs, compressor and cover modifications, fuel pump, exhaust mods including cat, tune and probably a couple of more things that I may have forgotten. To make it reliably add a built engine to the list above. Oh, what sort of fuel are you going to use to make said 400rwkW? Edit: how much? Anywhere from $10-25k.