968 cam and balance belts

[GR4]

Had the belts changed on my 968 today and while the car drives perfectly there is quite a pronounced high pitched whining noise coming from the belts. Technician who did the work tells me this is quite common and it will settle and quieten down with use. Reassurance please - Is this common/normal ? It's always a shame when the car comes back sounding worse than when it went in.
Thanks.

[Thom]

The whining noise comes from the balance shaft belt and is normal as the belt is new.
It should disappear with time when the belt stretches.

[AJLintern]

The cam belt is likely to stretch - they will need to re-tension it after about 1000 or so miles.

[Thom]

As far as I know the cam belt tension may not need checking since the tensioner is hydraulic on the 968 (not the case on any other 944).

[AJLintern]

The S2 has an automatic tensioner too - but it's been known to be unreliable. That's why they use a proper tool to do it these days.