About 100 miles after a rebuild and SC install a screaming noise like a siren started. It is not from the SC as it is present if that is disconnected.
It is definitely a vacuum leak as when on boost the noise goes away. In the attached video the noise is clearest at the end when the engine is switched off. Video is a .mov file and I cannot attach it or a link!!!
I have checked every vacuum pipe and all are sound wit( no leaks, disconnected the brake servo, and the only thing left is the inlet manifold gasket.
all suggestions welcomed.

 

Well it's tough without a video.
Does it sound like it's coming from under the UIM?

I had the OMP vacuum hose come off from the block located under the UIM.
It would make a horrible screaming noise especially once the engine came up to temperature.

When I would spool up the turbo the noise seemed to go away but I no believe it was just a case of not being able to hear under that load.
It maybe the same case for you.

I know its a real PITA to check, but it maybe something to consider.

 

The vent, not a vacuum, hose is firmly attached to the distribution block and the oil injectors have all been serviced and hold vacuum. The noise is really loud hopefully this link will work. https://1drv.ms/v/s!AugalL5KaYbxgqEuCFjjEQvobcDTIw
https://1drv.ms/v/s!AugalL5KaYbxgqEuCFjjEQvobcDTIw

 

Er. What vent, the distribution block is supposed to get pre-throttle body intake air. Since you're super charged, where did you route it?
Disconnect that hose and see if it's making the sound? If that's what it is, I don't think there's much you can do to stop the sound, in the stock system its suppressed by the intake system.