No way the ammeter should have a single set of speed nuts holding the gauge and wires. The factory used regular (and in most cases copper) threaded double nuts. One set of nuts held the gauge to the housing(with a special insulator washer underneath) and second set of nuts to hold the wires. As long as everything is clean and tightened properly, the system works just fine in a stock car. Now, you start adding accessories and upping the draw on the system, you'll need to make some mods.....one of which might be to bypass the ammeter. That would depend on the added load.
