MachSchnell

On idle or part throttle, generally with barely any throttle, there is a hideous whine/whistle coming from what seems to be the back of my intake manifold on the firewall side...almost sounds like a tea kettle going off, but it fades and seems dependant on either Throttle Position or Engine Load...I checked all visible vacuum lines which seem OK, and it is certainly emanating from the area between the firewall and runners of the intake mani (though it's possible that it's coming from the turbo area and just more noise is getting through that area than between the runners)...has anyone experienced this? It stops as soon as the engine is off, even when the turbo water pump runs, so I don't think this is the culprit, but given the location I can only think turbo or wastegate as the possible major culprits in the vicinity...

Any comparable experiences?