I once had a noise that would answer that description after replacing the camchain. Squeaking at only a particular rev range, and only under power. Because I heard it only under power I only noticed it when riding the bike, not in the garage. The fact that you only observe it warm also suggests camchain: a worn camchain is often quiet on startup, only audible when warm.
Solution was to take the timing cover off and adjust the chain guide carefully.
How long since you've replaced the camchain? I would expect to do it at 80k km.