Whistle noise when accelerating only on driving off Cold.

[Abertawe1972]

I have a Audi S7 4.0T 2015 where after not driving it for a week has started to make a whining noise and only when pulling off and the car is cold, the PVC has already been changed so i know the noise of that failing.
But this is a new noise that wasn't there before, the noise seems to be coming from the drivers side. When i boot it the noise goes and doesn't come back until cold again, the garage is telling me the turbo's are failing and need to be replaced (is this right?)
I don't want to be spending thousands of £ if it maybe something else, as i have no warning lights or any code or any smoke. I would welcome any advise on what to check, and if anyone else had this issue and how they fixed it?

 

[NHN]

Check for boost leaks with smoke system, but whistling is quite often turbos.

Could try to do a diagnostic static charger test that raises revs & turbo spool on a cold start, usually in basic settings ecu 01 module, although you may have 2 ECU's.

Assume the tone changes with the revs.

Find a proper vag garage to diagnose if you don't have vcds.

 

[Abertawe1972]

Check for boost leaks with smoke system, but whistling is quite often turbos.

Could try to do a diagnostic static charger test that raises revs & turbo spool on a cold start, usually in basic settings ecu 01 module, although you may have 2 ECU's.

Assume the tone changes with the revs.

Find a proper vag garage to diagnose if you don't have vcds.

Thank you for the response, as for the tone change i would say no it's just as i bring the boost in on 2000 rpm then it goes just after 3000 rpm. But as soon as the engine is up to temp, the noise goes completely which is puzzling.

 

[NHN]

Kinda points to turbo, but as the throughput & temps change, then makes sense, also engine temps maybe helping to seal any leaks, metal expands with heat & contracts when cold on a tiny level.