Hi DwDckQo,
have you found the issue/problem?
i according to my logs i have a similar problem.
Log shows 1,3 bar after 4000rpm, with WDGC dropping to 0%.
Boost gauge and a selfmade arduino boost gauge show 0,9 bar till red line.
Hyee, so
1) Bad WG Hose !!! Hose looks good, but ONLY after 1.4bar hose start leaking !
2) I made PID regulation (WG regulation) for my K04. Or better.. I deleted old PID regulation and replaced it with RS4 regulation (like this
http://nefariousmotorsports.com/forum/index.php?topic=12352.0title=). Now im spool around 3k rpm and boosting 1.2bar to redline.
3) Crap idle, bad idle fueling etc.. This was my mistake, because i bought injectors with bad pattern. SO i replaced them for OEM RS3 386cc injectors and everything is good.
Also i have brand new N75.
Where you have selfmade boost gauge ? Because original MAP is after IC.. Let me explain: I have also boost gauge just right after turbo, and when i have boost leaks turbo boost 1.5bar and MAP reads only 2100mbar