Supergoji

well, replacing the seats with 13lb frp's, two piece rotors, wheels, aluminum race calipers, maybe the hatch with a CF one.
not to mention aluminum drive train mounts. lighter CF driveshaft and carbonetics CF clutch kit (350z one weighs 25 lbs for entire clutch and pressure plate assembly)

then just tack on headers, Titanium Test pipes, Titanium Catback, Dual intakes, Tune. which would lop off another 30lbs+

and you've have yourself quite a quick car. a little noisy but fast and fun.

if money was no option people could have a 2900-3100lb Z with 400bhp