If you arent reaching 10psi until 6k then the arm is not as tight as you think and is opening very easily
after remove the sleeve arm from the wastegate pin.... and not loosing the circlip..
1: Undo the bolts - actuator bracket to compressor housing
2: wind the female end of the arm tighter about 4 turns then it was when you started, shorter for so its harder for the pressure to open, which = quicker response
3: hook it over the wastegate pin, this will require force, your man hands are needed here, wind the locking nut up against the sleeve, then using pliers up against the locking nut and your other hand maybe a crowbar, extend the arm over the wastegate pin.
4: tighten the actuator bracket bolts:
5: test drive, easy as you may have over tightened it and overboost quickly, so if you have let the car go cold and extend the arm, this will require your man hands again
thats it, just do it