Have just spoken to the guy who repaired the turbo,(has done thousands of them),and he has confirmed what i suspected,that the position of the actuator attachment in relation to the wastegate has probably altered,hence the drop in boost on the actuators current setting. Looking at the above posts i seem to have a similar trait of tailing off at high rpm rather than the boost increasing,will monitor this VERY closely.
If you see me kicking shit out of the car on Saturday you know why!

Thanks chaps.