I'm waiting for some log analysis, but right now we suspect a bit too much retard on the ign. timing, especially in that range, along with a adjustable boost actuator rod being screwed up a bit too tight.
We know from experience that the kit will maintain a smooth boost curve, even at higher boost levels.
8psi on Stage 1.5, with full exhaust, MAP sensor, 7psi Actuator
10psi on Stage 1.5+, with full exhaust, MAP sensor, 7psi Actuator
So just looking at sorting out what it is specifically.