I think you're right that 1 is the magic number, but I had to use a Tactrix and RomRaider to diagnose when it happened to me. Turned out that I pulled into my prefered gas station from the south instead of the north, which put my filler at the 85 hose instead of the 91 hose. Derp.Just to follow on from this, an easy way to check if your ECU is limiting boost will be to use your new OBD reader and check the IAM/DAM.
If less than 1 (or I think around 0.6 and lower?) it might start limiting boost due to perceived knock events, to protect your motor.
Should only take a minute or two to check.
If that reading is at 1 then I would start poking around your wastegate actuator lines, check for restrictor pill etc.