[wagonwheels]

Just an update on this as it's so annoying when googling and there isnt a conclusion to a problem.On doing some work on the car I found the brown boost control solenoid was cracked and leaking(the one that seems to control the big diaphragm and the back of the engine) on sorting it it was smooth right through the rev range.Not long after fixing it it also broke a exhaust temp sensor and now all is good.