Factory Boost setting

[Transporter]

How did you measure it?
Was it at idle speed or while driving?
The best way how to do it is; by driving up the hill (the engine at 80 deg.C) in 3rd gear @ 3000 RPM no less. Otherwise you don't get the max. charge pressure.

[t4tradie]

I have had a boost gauge fitted for the past 4 months just to get a idea. Boost readings have been measured over a variety of driving situations, from light load to full load at varying speeds.

[Transporter]

Well, this is not from the workshop manual for your engine, but it should be at least 13PSI - 15PSI measured under condition as above. Usually the T-piece is not the ideal connection.
How many km is done on engine?

[DVR68U]

also the line to the boost gauge can vary the amount shown , make it as short as possible and out of a hard plastic line , not rubber etc.
cheers brenton