Tapping vacuum line for boost gauge

Hi folks. Can you provide photos of an intake manifold vacuum line that I can use to connect my boost gauge for 2007 Mazda CX-7? Thanks a bunch!
 
I found the vacuum line from bov to intake manifold. However is normal for it to show negative pressure? Its reading -18 psi at idle. Any suggestions?
 

rsvinylgraphics

2008.5 MGM MS3
Contributor
:
2008.5 MS3
is it normal for it to show negative pressure? It’s reading -18 psi at idle.
That sounds about right to me. If the turbo is not forcing air into the engine, the engine is sucking air which is what causes vacuum. A negative reading on a boost gauge is merely telling you how much vacuum your engine is pulling.
 
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Is there a better place to tap? That doesnt show negative boost?


That sounds about right to me. If the turbo is not forcing air into the engine, the engine is sucking air which is what causes vacuum. A negative reading on a boost gauge is merely telling you how much vacuum your engine is pulling.
 
I mean. That is more negative pressure Than I would have guessed. -18. And only maxes at +5. Would that mean +23 total boost or just +5? I wold think just +5 but that is not stock then. I asked and there is no way to recalibrate it. Any thoughts?
 
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