The stock 460 system runs on 3 amps. No aftermarket systems use it. They are all 1, 2, or 4 amps for example. So using anything but 460 amps or speakers in a 460 system may work for a while, until something fries. I had an aftermarket head unit hooked up with an amp and 10" sub working straight off it, separate from the 460 system. Worked for quite awhile, but eventually it fried the whole system and had to replace everything. The stock system sounds decent, but it still lacks what the aftermarket can provide. Just replace it it you want it that bad, IMO.
2000 Mustang GT-Former giggle gas addict
1990 Mustang GT w/ Vortech V3
***resident gun idiot***