[Igovert500]

I have an alpine 12 disc changer and equalizer mounted behind the rear seats, and the head units mounted where the stock one was. But I still have the factory infinity speakers, no extra bass, and it sounds fine...plus you are gonna have to build a custom box to fit in the trunk.

As to which is better, the infinity or sony, I honestly don't know.

But, I would think that you could keep your cd player and factory head unit, I've helped friends put in sweet speakers and subs and they have kept the stock headunit, so I don't see why you couldn't.