I have a 2004 Cavalier sedan base model. I bought a factory radio from a 04 Impala, Not sure what trim model. I took the car to Chevy and had radio programed for my car. It works and my XM kit worked, reason for changing radio. Like I said the radio works fine but the audio just isn't right. All the audio is mainly comming from rear speakers. When I adjust the fader it adjustes but the I loose sound quality. The presets on EQ arent even close "Like talk, country, and etc." I tried another radio and it's the same way. Gets costly> The car only has the 24pin plug in the wiring harness, not the 12pin too. No factory amp. what parts would I need to straiten out the audio quality problem? I sure it has to deal with the speaker setup inside car. I even tried replacing the factory speakers with high end speakers but same problem.