What would you need to "convert" on the GTR to make it a track car, other than perhaps tires? And, this is a silly question. Should you track arguably one of the best track cars on the planet, or a 300zx that you say is already great on the street? Seems an obvious choice. And I say screw the people who say "learn to drive on a RWD beater". You have a fucking GTR dude. Unless you're planning on becoming a professional race car driver, who cares if you know the ins and outs of driving a RWD car? If the GTR is fun, go for it.