F90 whistleing at 4500 rpm

[smalldog]

Coming from the air silencer.... at 4500 to around 5300 rpms.
Sounds like intake air manifold vacuum, but is ear piercing in that rpm range.
Motor runs perfect. Everything is dialed in and no codes or alarms or buzzers. Just the most annoying high pitched whistle. Like the air silencer has turned into a giant whistle at those rpms.
Any suggestions?
Thanks much.

[boats.net]

If a carb model may have bad oring between silencer and carbs, possible something loose inside silencer or a small hole.