I added a vacuum gauge to my truck in May. I did this to get real time vacuum feedback because I was not satisfied with the time delayed ScanGauge MAP display.
The Canyon throttle by wire program has a real PITA feature in it. When between about 12 to 15 In Hg vacuum, I can lift the gas pedal enough to increase manifold vacuum by one to two inches. The vacuum increases, then the program takes over and opens the throttle plate just enough to put the manifold vacuum back where it was. If I reduce throttle slowly, I can raise the gas pedal about an inch with no change in manifold vacuum.
The real time feedback from a mechanical vacuum gauge makes it possible to get better control. This may explain why my mileage for the last 2000 miles is 38.0 MPG.
I bolted a small piece of aluminum to the gauge cup base, then added a piece of sticky back Velcro. Another piece of sticky back Velcro on the dash, and the gauge was mounted. I put the plastic vacuum line inside a piece of black shrink tubing because previous experience showed that sunlight will eventually destroy the tubing.