otay, so the car has a premium sound system by bose with a built in mid-sub in the back dash. on previous cars with the oem radio, i was able to attatch a converter to the back speakers to plug into my amp for a sub. some one told me that you can't do it with the bose systems. IS THAT TRUE? . if so, is there a different way to plug in a subwoofer system to the bose system??