So I managed to buy the shaker pro amp, mount, and subwoofer for $200. I have the base sound system in my 2014 GT. I don't have navigation or sync. My experience with audio is pitiful and I've heard that it's possible to wire up the and amp and subwoofer to the rear speakers somehow. If this is true, what other wiring/control units will I need? The last thing I want to do is crack open the console and replace the head unit. Any help is appreciated, thank you!