Thank you, that makes sense... I guess I didn't think that the gauge would read to the far left when at idle [negative boost]. If the numbers on the gauge are to be taken at face value (no pun intended) then:
if the engine'* at idle I have -10 boost.
if I am sustaining 70mph I have 0.
if I am flooring the pedal I have 4 or 5
For reference, I looked at DanThurs' gauges which seems to read differently at idle/ ignition on accessory. www.thurs.net/dan/personal/car/
Does that seem like an appropriate read? If so, I apologize for belaboring this. I'm trying to learn, and I didn't see any other threads with this question.