I tapped into the O2 wiring where the sensor harness connects to the computer harness, under the hood. It's got that little black bootie over it. I used a very small guage wire and run it inside via one of the heater-hose holes, along with the temp, oil press and knock-sensor wires. Easy. Though I paid like $65 for a _Camden Superchargers_ O2 display unit..... -glen