The customer has now reported back regarding the turbo boost gauge. The gauge is divided into increments with the highest reading before it goes into the red as one and a half. Turbo cuts in as per normal with a max boost reading of one and a half. When the mis-fire occurs, the needle then flickers at this point. I am now of the opinion that this vehicle has cam timing error and the overdue belt should be changed as a matter of course and hopefully cure the mis-fire problem. Unless I am advised to the contrary of course...

Regards

Pete M