I believe i have stopped the noise now from happening it certainly doesnt do it now, i was having a hesitation when it came on boost and was trying to fix it, i fitted a blanking plate to the egr to remove it from the system to see if this was the cause of the boost issue and low and behold the noise has stopped as in the video and i no longer have the hesitation either, so my guess is that it is being caused by the egr valve possibly the flap inside it isnt closing fully so there is air getting through when it should be closed. I havnt taken it off all i have done is to fit a plate to the egr valve itself at the front of the car side of it, you will see when you look. A friend gave me a plate a while ago but you could make one out of a piece of flat steel or stainless, just remove the pipe that goes between the egr and the intake manifold and draw around it as a template, it wont cost anything to do really apart from an hour of your time.