Ill assume for the moment you are running a factory Bose system. There is only one really good way to adapt this radio to a subwoofer or external amp. AudioLink makes a great adaptor for the bose system which will match the odd speaker impedence (1ohm) of the radio. Trust me, I tried many other adaptors before stumbling on this piece. It will allow you to use the factory amp to power just the stock speakers, the box also allows you to trim the crossover frequency going to them. Using the AudioLink, you can then add a subwoofer and this radio will ROCK! If you want to delete the factory amp, the unit will allow you to externally amplify all the speakers.
All the wiring is prewired!!! Just plug into the factory harness.
Search the net for AUDIO Link...The product is a PD4 or PD2 depending on what you want to do....