the lower half- like before 0 is your vacuum reading and thats on mmHg not psi but i get what you mean.. around 22-18 should be good on idle

 

Gotcha, thanks for the heads up. I always thought he whole gauge was on PSI.

 

So I didn't get too much time to work on my car this weekend, mostly because I was hung over from Halloween.

But I did get to re-wire the boost gauge sender unit power wire and it solved by brake light issue (it was oriignally wired into the plug comming off the master cy,inder resevoir).

My gauge is still a little off though (showed high 4 PSI boost and should probably be around high 5).

Not too concerned with it, but think it might be due to the fact that the vacuum line t-off I used on the regulator line (that came with the boost gauge) was kinda small for the hose. I used it because I didn't have a reducer at the time.

Gonna try and swap that out, and if that doesn't work.......oh well.