Any audio store is going to reccomend a $120 harness to retain your factory door chimes. Best buy LOL @ myself for even trying there... said that I would have issues with my airbags, abs, traction, and a bunch of other things if I didn't use the expensive harness...

The rest of this is personal experience and my own research, if you mess up your car, its not on me. I used a metra 97-2003 wiring harness in my 2004, non-monsson, non-onstar. I had to wire the switched power source to my gauges, because from what I've found, none of my fuses are switched. This requires manually starting the radio when I get in and turning it off when I get out. The only things I lost were the date on the DIC and door chimes.

My setup is a Pioneer AVIC-D3 with Alpine type r speakers in the back and factory up front (until I sell my 5 1/4 type r fronts for something 6.5).