I have the 60mm Air/Fuel Gauge with O2 sensor. I put the sensor about 10 inches from the front of the DP. It says in the manual that you have to adjust the gauge according to how close and how much pressure/heat it sees. You use the button on the back of the control unit to adjust it. Which one did everyone use? I think it goes by A/F ratio settings on the display. I think mine is at 15.0 (whatever default is). Is this where it should be? What should I use?