I could hit 32psi with leaking uppipes.
Id do like jap said, pull the turbo, fix wastegate actuator properly, put it all back together and see if that fixes the problem. If not, i gaurantee you its not the wheel causing your issue. Yes it moves less air, but not a noticable difference where itll be a smokey pig like yoyre saying it is. Seeing as how its all computer controlled, woudnt the wastegate opening up prematturely, have the fuel delivery cut back?? May not make any sense but its all i could think of with lower boost numbers AND lower egt's..