How trust worthy??
 

If your boost gauge is reading -20 to -21 vaccum on idle then is it a sure thing that you dont have a vacuum leak??? Or could it be possible for our cars to have a vacuum leak and still read normal??

RE: How trust worthy??
 

I had a vaccum leak even though my vac #'s were normal. Most of the time a vac leak is very small not obvious. If the leak is big enough to affect engine operation/performance-youll get a fault code or CEL.