"Pinking" noise from new 2.0d

[Sanzomat]

My new 2.0d V70 is making a sound very much like pinking (I thought that only petrol engines pink) It happens under moderate throttle/load between about 1500 to 2500 rpm. The volume of the noise is directly proportional to throttle position - more throttle louder noise, foot off, no noise. Even on cruise at a steady speed you can hear the noise come in when you go up an incline. Once you get above 2500 it pretty much goes. It does not seem dependant on temperature (not that I can tell as there is no temp guage on new V70s) but it happens from a cold start or when the car has been running for hours in the same way. Its pretty loud and can be heard easily over the radio. It is accompanied by a kind of whistling sound, almost as if the exhaust is blowing but as it very quiet when not on the throttle or even at higher revs I can't imagine its that. Anyone got any clues? Its going in for its 3000 mile "quality check" service next week so hopefully they will sort it but I wouldn't mind getting some points of view beforehand.

[Sanzomat]

Update on this post, in case anyone else has something similar. It came back from the 3000 mile check unsolved - they (Johnsons of Gloucester) said it was perfectly normal. I mentioned it again when booking it in for my 12,500 service which was done yesterday by MRG in Chippenham. MRG obviously checked it out properly as they discovered a "loose intake chamber to turbo" Not sure exactly what that is but I believe its some kind of plenum. They said the bolt that should hold it tight was missing altogether. as the pinking noise hasn't altered since the car was brand new I'm guessing this must have been the case when it left the factory. The car is much quieter and smoother pulling in the 1500 to 2500 rpm range so is now what it should have always been. I'm a bit unhappy that it wasn't sorted sooner but I'm pleased it is now, and that I wasn't being daft being concerned about it. Thanks very much MRG if you are out there! Highly recommended.