Good to know about not having to run a MBC with those WG springs.
Its a OEM style Autometer 30/30. I recently got a Aeroforce scan gauge and I have boost set up on that where it reads at the MAP sensor. Going to see if it fluctuates on that too. Could just be the boost gauge or a leak to the boost gauge. But when I had the dash apart it was clamped on there good. But who knows might have a needle leak or something. Would have to boost leak test the car with the dash up to see if it is leaking at the gauge. Sorry for the ramble in my original post.
Just for clarity, the Aeroforce ScanPro reads the manifold PSI from the PCM via the OBD-II connector, not the MAP sensor directly.
Also, lots of guys have used just the WGA to control boost since 2003 !