i recently bought a 1991 300zx NA, i am very satisfied with it, but i was interested in upgrading it a bit, i was wondering if any one could tell me some stuff about these parts in a 300zx and if the make a difference to performance. would headers make a difference or is the stock exaust manifold close enough to headers? would a cold air intake or just a new intake make a difference? also i know nothing about an ECU for this car. so any knowladge about them would be helpfull. this car is 100 percent stock and still has the original 222 hp, my hopes is to get the car to remain reliable, but also respectably fast.

pop charger, exhaust, headers, lightweight flywheel, all will give you a little bit more power and remain reliable, but big power can only be obtained with twin turbo conversion.