It'll read "actual pressure".
Note that "actual pressure" can be negative (a.k.a. vacuum) or positive (a.k.a. boost).
When you go from idle and start to open the throttle, the gauge should move from 17-19 in.Hg of vacuum and goes to "0" vacuum (which is "0" boost).
And if you still keep pushing your right foot on the pedal , the needle will keep going from "0" boost to 1 psi, 2 psi, 3 psi ..... Then when you lift your right foot, the needle will move back to vacuum.
watch this clip:
http://video.google.com/videoplay?docid ... 8322914594
Note that "actual pressure" can be negative (a.k.a. vacuum) or positive (a.k.a. boost).
When you go from idle and start to open the throttle, the gauge should move from 17-19 in.Hg of vacuum and goes to "0" vacuum (which is "0" boost).
And if you still keep pushing your right foot on the pedal , the needle will keep going from "0" boost to 1 psi, 2 psi, 3 psi ..... Then when you lift your right foot, the needle will move back to vacuum.
watch this clip:
http://video.google.com/videoplay?docid ... 8322914594