Jon,

The dash pops out pretty easily, and the radio is just a couple of screws after that. As for the rear seat, it's very easy to get out, too. If you'd like, I can e-mail or fax you a copy of the Crutchfield master install sheets and you can see how easy it is.

The Grand Prix Store (www.grandprixstore.com) and the Club GP store (www.clubgpstore.com) both sell adapters that let you use your aftermarket HU with the steering wheel controls and interface with OnStar. The only bad thing is you lose the interface to the Head Up Display. I don't think anyone has come up with a solution for that one yet...