Question on psi on turbos
 

I purchased a 1994 300zx twin turbo a couple of weeks ago. Add on are center intercooler exhaust system , cold air intake, Jim Wolff chip. The car has lots of power and boost. But when I hooked up an after market gauge to it it says I am only pushing 2psi.. To me that doesn't seem right for what the power and boost it is delivering. The stock gauge says 9psi but I have heard that those are not that accurate. Can anyone give me some pointers on what to look for or what could be wrong?
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Pics of the aftermarket gauge?