I would like to upgrade from my factory tape deck. Right now it has 6.5" (I think) seperates up front and some smaller coax's in back. I've heard talk about some factory amps. I would like the factory tape/cd/radio combo. How do I know if I have the amp or need the amp or need some adapter? Where would the amp be? Also are there different wattages associated with different head units, is there a preffered factory set up that I should look for? Any help is greatly appreciated!