need help identifying aftermarket 300zx parts?

Question

what are these

Random Tech 3" Downpipes
Random Tech 3" Testpipes
Polished plenum
Polished fuel rail
JWT Pop Charger
HKS Wastegates
Fidanza Lightened Flywheel
Z1 1pc Driveshaft
Greddy Catch Can

Answer 1

DOWNPIPE - wider diameter pipe, provides better exhaust flow, usually increasing horsepower and/or efficiency
TEST PIPE - is usually the term used for a straight through pipe that substitutes the catalytic converter. Basically, removing the catalytic converter. Proven on some cars to increase horse power, pending on vehicle may be minimum
PLENUM - plenum is also part of the intake manifold, basically the breathing part of the engine, where the air enters and is usually divided into each cylinder equally. Yours is just polished, so no performance improvement, just for show. Unless, meant to say port/polish, which would be the inside of the passages are smoothed out to help the efficiency of air flow.
FUEL RAIL - the rail which carrys the fuel to the cylinders, like the plenum just polished for looks
JWT - is Jim Wolf Technology, "pop charger" is just there name for an intake system. Different engine air filter which allows more air to pass through for slight increase in horsepower, turbo model vehicles usually get a better gain.
HKS wastegates- Assuming you have this then your vehicle does have turbo, part of turbo system
FIDANZA - lighter flywheel, part of manual transmission assy, usually allows car to rev easier/quicker
DRIVESHAFT 1pc - ? dont know ?
CATCH CAN - oil catch can, unused exhaust fumes come out a breather valve and is recycled. usually, there can be very small amounts of oil in this air, and the catch can basically prevents this oil from entering the intake system of vehicle

Hope this helps

Answer 2

Besides expensive? The glaring omission seems to be Garrett Ball bearing larger turbos and larger Z1 motor sports inter coolers. The parts you have make the 300ZX put out 325 hp at the wheels about 400 Crank power