Does anyone of you guys have an idea what might cause following symptom:

With cold engine boost 1,2 bar ,with heat soaked engine boost varies between 0,8-1,0 bar.

Friend's car; LR Super 65 turbo ( one year old ),MAP,dual port wastegate ( original body just converted with new "bell" ),BoostSciences MBC.

 

I had a leak on my BOV connection on the boost connection. It would only leak when the rubber hose got warm and as boost developed. Everything looked OK when inspecting because the vacuum at idle would suck it back on good and snug until the next boost.

 

If he has datalogging compare the pressure differential between the cold and warm operations. If you are picking up boost a good 200 - 300 RPM later than normal then you have a pinhole leak somewhere. Take into considerations the excess fueling (cold start trim), and ignition trim (cold start, if any) when making an assesment.