Hmm I don't believe that's how it's supposed to behave, and I'll tell you why. Here are logs from my own stage 2 Cobb back from 2009 when I still had an AP. I had a full 3" catted turboback and AVO TMIC. Regular off the shelf stage 2 Cobb, 93 octane.
Those are 3rd gear runs, and you can see what the temperature is like. Notice how I actually hit 16 PSI, and my wastegate isn't capped out like yours is.