I really can't stand the Bose system and like to put my music on thumb drive or mp3 cds. Can I simply add an aftermarket head unit and use harness for power and ground only, take out door speakers and replace with aftermarket and run new wire to them from an external amp. my wife has the Pioneer 3200 with DVD and I really like it and would probably go with a Alpine PDX 5 for the amp. I would have the bose stuff to put back in if I ever sell the truck.

Yeah, that would work great. Those Alpine PDX amps are pretty sweet.

yeah you can run a external amp real easy just need the power ground switched and remote wire used in the new head unit and some patch cables ran to the pre outs

I think you will need an adapter to get the stock harness to run the aftermarket head unit. I needed one in my 05. After that its plug and play.

well yeah you will need a aftermarket intergration harness you can get em at walmart that are gm specific for 03 ups for 40 bucks you will need a install kit and antenna adapter too