Sounds like an xPlode HU and factory speakers. Invest $375 and buy a decent system - Alpine HU and Infinity speakers (5x8 in all 4 doors). Bypass the factory amp totally and just use HU and speakers. You can all do it yourself in about 3-4 hours. Sounds incredible with my iPod.
Note: if the speakers still do not work, you may need to trace the speaker wire...
