First thing to do is to get yourself a gm service manual. I highly recommend it. Next, try to get the most complete system you can get with wire harness pigtails or complete harness. I bought a complete unit (receiver, gps antenna, display panel, center dash panel, pigtails) out of a 2008 cts. I bought mine on eBay, or you can try a junkyard. These units are locked once they are removed from the donor car, so youll have to get it unlocked. Again, eBay was my friend. The next step is to take apart the center dash panel. The procedure is in the service repair manual. Then remove the receiver. On mine, there was three connections on the back. There was a big black 44 pin connector, an antenna and a satellite antenna connection. All three plug directly into your new receiver. Now comes the fun part. You'll have to supply grounds, a vss signal, and ign power. I found one power source in the 44pin receiver connector. The other power source I found by prying of the left dashboard access cover by the drivers door. For the vss signal, I tapped into a wire (green and yellow I think) on the driver side valve cover in the engine compartment. The gps antenna is located under the riverside defrost vent. The parts that I needed were wire taps, shrink wrap, solider, wire, trim push clips, and some trim screws. The display panel bolts right up. You will need to get some clips and screws to secure it. The new receiver bolts right in. Put in your new dash panel and if you did everything right, you should have factory navigation. I haven't figured out the sound part yet. I think I'm gonna get a premium amp with the pigtails and make a new harness to add that fourth connection to the amp.