in my 17 WRX Id peak at 20-21 psi in warm weather, but in winter or colder weather, esp under 30 deg F Id see peak boost 15-17 maybe. Figured the ECU limited boost depending on temps. It was pretty consistent.
In my 18 STI, peak boost in cold weather (30s) is like 14-15, when it hit 70 for a few days I saw 16-17
Its consistent.
Yours however sounds like they left a rag in the intake or something. Just not right