Ok, I joined this forum just to jump in here.
I am also hitting 90.2 WGDC and getting low boost (like 16 psi). I have a 05 Legacy GT - 2.5 with a vf40 - you know the bit.
Read my story here.
http://legacygt.com/forums/turbo-powert ... after.html
This steps you through my dilema. I am still stuck.
Cliff notes:
Ran 18psi fine with like 86% WGDC flat.
Installed K&N intake - loaded a TDC Tuning base map they made for the intake
Did a log - getting 15 or 16 psi peak (3rd gear always) - WGDC dips down in low RPMS when before it just was flat the entire rpm range
TDC send me a realtime after looking at my logs - still having a dip in WGDC
I then installed EL headers - still getting low boost and the din in WGDC - even after a few realtimes
So I went back to my old STG II map, where I used to get 18psi and had a 86% WGDC. Now I am getting 16psi and 90.2% WGDC. The WGDC is flat again... but now really high.
So on the same map - I am getting the effect you see above.
So... now I need to figure out what would cause the ECU to jump the WGDC to 90.2 on its own... did I bump something on the install? I cannot find a boost leak, but it is hard to tell just when the car is idling.
I am clueless... thinking about talking to Christian at COBB and see if he has any insight.