I realized this evening that I can reproduce the noise without the engine being under load. It happens _exactly_ at 3,000 rpm when just revving the engine in neutral. It happens as I cross 3k when accelerating, and happens again when I cross it decelerating. If I hold right at 3k rpm, I can get the squeal to just sit there and make sustained noise. I tried to capture it on video. If you listen closely, you'll here it a few times in this clip. For the last few seconds I have it held right at 3,000 rpm and it's making the noise constantly. It's actually pretty loud even though it's a little tricky to hear in this video over the general engine noise (easier I find with headphones). It's really hard to pinpoint, but I'm pretty sure it's not coming from anything attached to the belt. It sounds like it's actually coming more from the front of the engine on the driver's side, but I could be mistaken.
https://vimeo.com/440509054
Is it possible this is caused by some variable valve timing or variable intake manifold system? Is there anything that switches over around 3,000 rpm on these engines that might be causing this? Any other thoughts on things to check?
Thanks again!