John, thanks, to do that, how could I blank off the pipe that goes from the solenoid? I assume that I can just get a 2 way connector to join the two pipes (or can I blank make something temporarily block the solenoid outlet on the T piece?

I'm guessing here, but if the problem is still there when doing as you mentioned, it means that the problem is definitely boost creep due to the wastegate?

 

What amount will I need to port the wastegate by? I assume that if the penny still covers the hole, then I will be OK?

 

I would port it as much as you can to get a good seal - leave about 1mm rim. If you need to use a stronger actuator to hold top end it is better than it boost creeping.

Just pull the hose off the actuator and seal the end of the hose with a screw.

 

will try, thanks for your help - just gotta get it past the MOT today!