Losing Boost at about 5000 revs

[rogwick]

wish me luck as most Mazda mechanics don't know there spanners from there screwdrivers.

Lol its like how folks don't know "their" from "there" haha, all the best for the service, hope they sort your problem

[Doug_MPS6]

From your description it sounds like premature waste-gate opening

[J Alesi]

From your description it sounds like premature waste-gate opening

I think you are right, how do I know for sure.

Mazda didn't find anything wrong, but when I ask them to look at it properley they didn't want to waste their time!!!!

Can the waste gate be tuned or does it need to be replaced?

[Doug_MPS6]

Depends on the tuning software. I assume the Mazda system can do it.
You can specify maximum boost with the Standback, which I assume determines waste-gate function. Others here have had waste-gate issues and have replaced the operating solenoid. Suggest you search the threads with "wastegate". Chs.