Are the "premium" stock nakamichi decks upgradable? The cars i was wondering about are a 200 RX-300 and a 93 SC-400. I want to add a sub but i dont know if there are any RCA outs or anything on these head units.

 

If you have an SC the nakamichi and pioneer systems should have a stock 8inch on the rear deck. If you dont then you were cheaped. The Head units dont have RCA outputs however you can get an adapter called a line out converter which will transform speaker inputs in an RCA connection. Find the wires next to the stock amp in the trunk is not easy. Go to a professional this is a normal daily task. My recommendation is to get a FREE-AIR 8inch JL or DYNaudio sub and a good amp for the rear. Bass may be all you need. GOOD LUCK