Update: Took off the SC snout and changed the coupler and oil. Reassembled and now the noise is louder.

Here is what it sounds like at idle: YouTube.

Also now it idles like sh!t and is setting a P0171 code, bank 1 lean. If I take off the SC belt the noise goes away and it idles fine. Is the SC toast?
The vacuum fitting under the snout was all dry rotted so I changed that.