I started with a standard 200SX many years ago. It evolved over the years from standard to a dedicated track car which makes around 580bhp now, with dog box, cage, coilovers etc - horrible on the road now, but very quick on track.
I think the 350z makes an excellent road car - pretty good on fuel, easy to drive around at low rpm with enough torque to pull you along. Great handling as standard too. I do miss the mid range torque of a turbo charged engine though.
The 350z is going to be an on going project - I'll probably keep it as a fairly sensible road car for a while and then tune the engine for track use.