So now I'm looking at getting an amp and some speakers. It adds up so quickly... haha. Anyway is it understood that you can install any amp to any aftermarket head unit. I ask because I have an aftermarket head unit and am concerned about the HU'S amp outputting only 22 watts @ 4 ohms. I was looking at the Alpine MPR F-300 with the 6x9 Infinity kappa's for the rear. Still not sure about the front. All I see in stores are 6 1/2" not 6 3/4". Also I was told to be concerned about depth. What is the maximum depth I need? Sorry best buy and P.C. Richard and Sons aren't very helpful (Too bad circuit city closed). If someone might suggest some speakers for the front door panel? Thanks guys. I really appreciate the help.