Mustang, I think we are talking about the same guage. It needs to be connected between the air filter and the turbo, that way it reads air restriction, vacuum, caused by a blocked or partially blocked filter. The guage I have holds the maximum reading until manually reset. Gives real information on what's happening while going down the highway under load.
The wiring is always fun but I like to find how things were originally set up to work before I start redesigning things. Sometimes the designers really did have a good idea and it's the people between the designers and you that caused the problems.
As for my new challenge, while going in to get some fuel and propane today I got about two miles from home and the alternator froze. It was doing some not nice things to my new belts. I managed to loosen the belt adjustment to try to limp home without destroying the belts. The question now is it the alternator or the vacuum pump behind it that is frozen? Anyway I guess we all know what I'll be doing tomorrow.