if weight reduction is your new path to enlightenment then EPRacing have made a whole range of carbon fibre parts to reduce weight. including the doors, front wings, bonnet. there is also a Carbon rear boot available.
getting rid of luxuries helps as they all weigh a bit, so throw the aircon, electric seats, radio out and all the speakers removed.
the money you'd spend lightening the car out properly you'd be pushing supercharger money.
the 350z is not an out and out race car. its a sports coup GT cruiser. the engine is designed with lots of torque to allow fast long driving with minimal gear changing. the car is designed to eat miles up and eat them quickly.