mr. harris, you need to start by determining what impedence your sub is at. You do this with a voltmeter. Leave car off. Disconnect the amp from the speaker and get a reading, it is probably around 1 ohm. You will need to find a sub rated for that impedence with a power rating from 50-250 watts RMS. You will also want to know if the new sub will fit into the hole on the rear deck. You may have to drill out a few holes if the new sub doesn't line up. The main about wiring is not to confuse what is positive and negative and never let wires touch as you will surely blow a fuse, so leave your car off. My 2001 maxima had a sub that was rated at approx. 1 ohm and i found at car domain a DVC(Dual Voice Coil) free air(Mounts on rear deck without an enclosure) 2 ohm sub. I wired it in parallel and it becomes a 1 ohm load that the Bose amp works fine with. Make sure you think it through before you remove/disconnect or wire anything.