Underdrive pulley gimmick!

[Unit 5302]

While you're kinda correct, you're assuming that both the 65amp and the 130amp are at least linear in their power production at idle. The stock 65amp alternator could be putting out as little as 15amps at idle, where the 130amp can make 60. The G3 alternator also uses a larger diameter pulley than stock 65amp alternators. If you were to take a used alternator from a 94-95GT and put it onto an 86-93 GT, you'd have a slight underdrive effect right there. I see no logical reason to run a fuse on the alternator if you wire it properly. The 94-95GTs use the 130amp without a fuse, why would you have to put one on a fox?

By the way, I have a 130amp alternator, and it charges with the rear defrost, max A/C on high, headlights and foglights on at idle. About 14.0 volts last I checked.