You can get an adapter to keep the factory steering wheel controls w/ alot of aftermarket headunits. It's made by PAC, I forget the exact model right now. I have it installed w/ my pioneer avic-z2 head unit and it works great. Just need to make sure the radio you choose has a wired remote input, and then get the pac adapter that has the wired remote output and your all set. Adapter is about $60, you can program the factory buttons to do any function you want for the head unit. I have mine where "mode" changes the input, "next up, next down" changes the cd track and "volume up/down" is of course volume.
