I'm so pissed about getting raped by the stealership for an aftermarket stereo that was a huge downgrade. I got it just for GPS but the unit's GPS is so awful it takes me in circles and the screen randomly blacks out. Anyway I wanna switch back the stock head unit. It allows Pandora right? So I'm not sure what wires have to be changed. I had the aftermarket system installed. I also know I'm gonna want a 5 channel amp. I've already upgraded all the speakers. But I also want a subwoofer in the stock location. I've seen someone do it on here. A little plastic trimming required but no big deal. So looking for help on what parts I need to buy. Thanks.