Has anyone with the factory Rockford Fosgate system replaced JUST the head unit? If so, did the factory speakers still sound good and were you able to utilize the Fosgate amp and sub and all the power? I am thinking about a new stereo but don't want to lose the sound we already get from the factory equipment. I just want to purchase a stereo and the adapter to use the steering wheel controls...i don't think there is any need to replace the speakers. Any info would be greatly appreciated!