Boost Gauge help with Pictures

[Bean]

well if the boost gauge is connected properly you should have vacuum reading at idle (below 0 bar). The fuel pressure regulator line should actually see the right signal for the boost gauge as it needs to know the boost pressure to compensate the fuel pressure compared to boost (think base fuel pressure + boost = actual fuel pressure; as without it the engine would run lean due to the actual fuel exiting the injector under boost would be less than anticipated by the ECU as it needs to fight against the higher than ambient pressure). Although I personally wouldn't T into that to avoid any tampering of that signal due to the gauge.

hope you're still with me so far

anyway as it's been ages since I've seen a GZE manifold up close I can only point you in the right direction. On a regular 16V 4AGE there is a triple take off just behind the cold start injector (that thing with the almost square plug) on the plenum. I assume something similar would be on the GZE.
Try to follow the path the air takes: filter - SC - (Intercooler -) throttle body - Intake - valves. now on th intake part there should be a couple of small rubber hoses (maybe a bit hidden away on the back of it) where you can T in or even use a spare nipple which is blanked off. As said be sure it's some where AFTER the air has passed the throttle body else you wont see vacuum or a proper boost reading.

Hope that helps - if not take a bunch of pictures all around the intake side in the best quality you possibly can and I'll try to help out from there.

Worst case scenario is you tap the intake manifold and fit a nipple yourself.