with all the money ur gonna spend on the engine and fitment and all the other minor headaches like wiring looms and what have u I'd strengthen the RB25DET, like cooler, ecu, turbo, bottom end forgies fuel pump injectors will have u a very quick car might cost u a couple grand over, but remember the RB26 is obviously gonna be standard which means ur gonna have to make it quicker, more money on top of that... plus ur line is rwd which aint gonna be that much quicker than the RB25DET....just my opinion in the end its ur car do what u like bud...