[elhigh]

I got a mechanical vacuum gauge from O'Reilly's and plumbed it in and was really happy with it...for about a month.

Then I noticed the vacuum was creeping up and up. "Cool," thought I. "I'm getting better."

Not so. At rest with the engine off, the needle would come to rest at 5, then 10" of vacuum. With difficulty, I painstakingly took the gauge apart, reset the needle and put it back together.

It happened again. My gauge shows about 12.5 - 15" vacuum with the engine off. It isn't helping me over time, I can only use it for instantaneous improvements in pedal position.

I would vote for an electronic gauge, if only for the fact that it should recalibrate itself back to zero every time it turns off.