I'll give you a for this one... maybe the question here should be: How "should" the factory in-dash amp gauge be reading under normal driving conditions? I would say mine is:

In gear, stopped, foot on brake, headlights on = Reads about -20 on the gauge

In park, idling, no headlights = Reads just slightly to the "-" side

Cruising at a constant speed, lights on or off = Reads maybe up to +20 on the gauge

Under heavy acceleration, it will sometimes jump up above +20 but just for short temporary bursts. I'd like to hear from others about how their gauge behaves.

Darren