I have currently set up subwoofers in my car. I had to use a line output converter to get an rca signal using the rear deck speakers. I have also hooked up a wired fm transmitter to play my ipod. it works ok, but i had the exact same subwoofers and amp in my old car, but hooked up to a kenwood head unit, not the factory unit with adapters, and the quality was much better. I would like to put this kenwood unit into my new car but i understand that there are problems with removing the factory unit. How do i retain the onstar capabilities as well as the DIC center. i have heard that the factory unit is required to run the trip computer and other functions on the DIC, all of which i do not want to lose. Is there any way to do this with an aftermarket head unit.