S3 squealing noise

[Martynhill]

Over the past few day my s3 has developed a low pitch squealing nose on boost any ideas what it could be thanks

 

[JonoPhilpott]

I'd take your intake of the the turbo and feel for play in the shaft if I was you!

 

[<tuffty/>]

Boost leak is the most likely cause... a screech on boost can also be cavitation on mapped cars with standard sized OE or silicone turbo inlet pipes

VCDS for fault codes would a a useful idea and smoke test for leaks

<tuffty/>