That gauge should have come with a black, orange, and red wire. I have wire out the yazzoo with from my gauges. Look in your packaging again. It should be coiled up and wrapped with painters tape in the box with the gauge.Thanks for the help, I assumed that if those wires were needed they would've been included with the wire harness like the Autometer gauges did. I guess the difference between my boost gauge and rail pressure garage is the boost is a mechanical gauge and the RP is electric. I'll head out to pick up some 16 gauge wiring.
I never really understood the dimmer harness. I have my wired to my dimmer switch and the gauges dim with the rest of my indash gauges. Ive wondered if I was I was supplying less power to the gauges...but they dim and no issues so far.Or you can order the r72022 dimmer harness. Because of those I have now 6 loops of those red/orange/black wires laying around. I like the dimmer because I like having my gauge backlighting on all the time, but not full brightness.