Ya it is possible to up the boost by bending the actuator arm, but it could be your guage aswell, it could be both, you could actually boost .9 or 1 bar and not know it or obviosly .65 and the guage reads too high.
the best is to borrow a proper guage like VDO or Greddy or something from a tuner, connect it and see what it really boosts, or ask them to do it on the dina...