Wondering if you guys can help me out or if this is even possible. I want to keep the Mach 460 system including the 6 disk HU in my 03' GT but I want to add two 12" subs and amp of course. I know it's not the best way to go but I don't think the Mach system sounds all that bad for hopefully just being internal speakers. Anyway, if you guys can let me know what I need(special wire harness etc.) it would be much appreciated. Or if it's not at all possible....let me know. Thanks in advance. By the way, I'm looking at two Pioneer Premier subs(400watt rms/1000watt max).