Crutchfield and most aftermarket install manuals say that you have to bypass the factory amp and rewire the whole thing. This IS NOT the case at all. I don't know where this comes from. A plain old wiring harness adapter and Euro style antenna adapter is all you need. You can do it yourself in 30 minutes. If you look in the Audio, Video and Electronics section of the forum, there is any excellent how-to with good pictures and a list of what you need.