amp gauge

why bypass the stock ammeter with an aftermarket one? just curious....

The wires on the back of the ammeter will go to the same place on the aftermarket one. There is a + and - on both.

If you are replacing it with an aftermarket VOLT meter, that is a bit different. You can leave the ammeter alone and just install the volt meter and run both or, you need to connect the 2 large wires from the back of the ammeter together and then the + post on your volt meter gets connected to a 12v source that is only hot when the car is on (like the + wire going to your heater or radio). The - post on the volt meter goes to ground.