pertronix ignition question

Mopar Ballast resistor is current limiting as well as voltage limiting as it gets hotter. 7-9V is what it passes hot, and they get pretty freakin hot (stepping 12V down to 7-9 releases some heat). Im sure the Pertronix can handle 12V. Try running an MSD6 box through the ballast resistor, probably will crap out as soon as it gets warm.