I ripped out my full mach 1000 system last year. The way Visteon made this system was almost like they intentionally wanted it to be a pain in the ass for you to upgrade the system (aftermarket sabotage). I spliced into the existing tweeter wiring for my door and rear deck component speakers.
I will probably sell my full mach 1000 system soon. I am a music producer and my ears needed more quality and output than the mach 1000 system provides, although, the mach system does get very loud for a stock system.
Damn my sensitive picky ears!