I have one in my LS base Cobalt sedan. I had the now defunct Circuit City install. power is the basic install, wiring to get sound sounded a little tricky, but I dont really understand alot of that stuff anyway, reason I had the pros install. Any decent shop should be able to hook it up. You will need an amp to power the sub though. If it is done right it will sound better than the factory set up. I also Dynamatted the trucnk before install.
If you do buy, you will need the special bolts from GM to bolt it to the trunk wall in the factory location, nuts from a hardware store. To put the nuts on the bolts, get a piece of rubber tubing with an inner diameter of the nut, put the nut in the tube and use that to start the nuts on the bolts, then torque down with an deep socket and extension. Then let an audio shop do the wiring and save a couple bucks.