[relative4]

'08 335xi E90 MT, MHD stage 1+. I'm chasing a nasty underboost that started suddenly a week ago. I've been boosting great, then as I charged up an on-ramp, suddenly I got a 30FF and have been boosting like crap ever since.
The turbos are OEM Mitsus with less than a year, about 6000 miles, on them. My target boost is 14-15psi; I'm spooling slowly and peaking at 10-11psi.
Because of the sudden onset, I started by smoke testing. Found a couple minor boost leaks, sealed those and no change.
Then I tested the vacuum system. Plugging the top of one canister and drawing vacuum on the top of the other canister, it holds vacuum perfectly. Drawing vacuum on the boost control solenoids and applying 12V to the solenoids operates the wastegates normally as far as I can tell. Both solenoids measure 12.6 ohms.
I again plugged one canister top and hooked up my MityVac to the other canister top, and started the car. I get 20" of vacuum. I thought this was normal, but now I'm seeing some mentions of 25" at idle. Does anyone have solid information on what the vacuum pump should be pulling? Thanks!