Has anyone ever hooked up a after market sub and amp to the factory navigation head unit in the 2011 model platinums? i have a sundown x 15 with a 3500 watt amp that i’m wanting to put in my truck, i have all the wiring for the aftermarket amp i’m putting in and the stock sub is out i just don’t know what to do with the stock sub plug in piece and the factory amp, does anybody know what the best thing to do would be?