Low Boost, MAP sensor question

[rsaviper]

I'm seeing about 20-21 psi at full throttle and the MAP values are consistant 34-35psi. However, at partial throttle up a hill i can build over 25psi but the MAP psi reading will drop down to 1-3 psi. Does that seem normal for a MAP to do if I have a boost leak or am I looking at something else being wrong? I'm about to put it back to stock to make sure its not a tuning problem. I don't know when the 20psi problem started, wish i noticed it sooner to see if it was related to the tunes or what.

Mods: MBRP 4" straight turbo back exhaust, SCT x3 with gearhead tunes, and monitoring gauges.