turbo noise like a siren

[WScott]

Hmm, not sure what is happening. From about 15-25 boost i get a sound much like a siren. And yes I looked in the rearview.
Louder than a whistle, dunno just started today. Overdrive off and pulling a hill boosting like i said starting around 15-20 and up. It is quite loud. No power loss no other noises nothing unusual. Just this loud high pitch howl.

Any ideas??

[vitalidle]

Hmm does it sound like metal to metal sound? Might be worth pulling the intake off the turbo and check for any play in the shaft.