when I redo anything electrical on my Contour, I leave the factory connectors the hell alone and make plugs to fit the existing harness. This way if I decide to swap back to the old stuff there is no problem and also if some weird problem occurs I simply unplug and redo instead of butchering the harness to shreds. On my factory speaker wires I simply used two spade connectors and plugged them in and then hooked them to the aftermarket pigtail to direct them to the speakers.
