I now have 3 cars (2x AEB 1.8T on Giac PC16, larger than K04 turbos, high flow manifold), 1x 2.7T stage 2+ JFonz, otherwise stock) that all show similar systems:

Boost pressure 'swings' (amplitude 3-5 psi) from ca. 10 psi on, mid range RPM.
I call it 'boost pumping'.

Obviously, something is causing the 'system' comprised of:
- tune (N75 control)
- N75 valve (1 is brand new OEM, the other OEM but older)
- wastegate actuator spring (AEB have slight stiffer spring)
- turbo (AEB have larger than K04, 2.7T has stock)
- exhaust ingoing (AEG have high flow manifold, 2.7T has stock)
- exhaust outgoing (AEB have 3" DP, 2.7T has gutted pre cut and main cat delete)
- wastegate flap (all stock)

Any suggestions or ideas how to 'detune' this swinger?

I will upload some crappy video.
But its pretty straight forward: Boost swings several PSI at a frequency of maybe 0.5 to 1 Hz.

I had tried (on the 2.7T) to log in highest gear (VAGcom, slow). The resulting graph just describes the above. Will dig that out as well.

Currently working on getting another logging software to run on the AEB (waiting for cable) to hopefully collect some better logging data.

VCDS is like the slowest logger on the planet.. you should be able to run the Nefmoto logger and me7logger on your 2.7, not sure about the 1.8t

any trouble codes?