So I was looking into getting a touch screen head unit to replace my stock radio in my 2012 GSR. I dont need one that has navigation. I dont care about the disk changer. And I am looking for one that will work with the BT that is already in the car and that can be controlled by the controls on the steering wheel.

 

Most of your new head units now offer an additional cable (you have to buy separate), that will let you use your factory steering wheel controls. As far as Bluetooth is concerned, it won't piggy back to your existing setup. If the new unit offers Bluetooth, then it will be self contained and ran by the units own software. Some units come with a mic and some you have to buy separate.