2008 YZF 450 - Valve whistle?!

I'm not sure how else to describe it, but after about 10 hrs on the complete bottom-end & top-end rebuild (minus any head/valve work) it just started making a higher rpm noise?

I can't describe it any other way other than to call it a 'valve whistling'?

Here is how I can induce it, but it always happens around these same conditions lately:

2nd-3rd Gear, higher rpms, kinda like when your towards the end of a straight and you don't really want to shift again, since your almost to the next corner. I'm not hitting the rev limiter, but I am pretty far up in the rpm range when it happens.

Like a 'ssshhhwwwiieesssss'

Any idea if I should be concerned, or could it just be another version of those noisy yz valves?

No other wierd noises just putt-N-around though? Power is good, shifting, clutch, etc, everything else is working pretty darn good!

Edited by NewMexican
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