Hi Dazz
Thanks for the speedy reply. I have checked, and had checked by another mechanic, that they fitted a new turbo and it certainly new. Do you know if there's any kind of diverter valve on these engines. I read a couple of posts from VW forum which sounded like the same issue and they mentioned a diverter valve. I did also think it could be an exhaust manifold leak.
It will be a VW blow valve for petrol motor- not on your car!
Appears the car runs ok so-
The rasping sound could be pressure escaping post the turbo.
I would search the large rubber hoses leading from turbo to the inter cooler.
Look for Cuts or fractures, loose clamps, leak in the inter cooler.