Roadkill,
I have a tach on my DF and I am seeing about the same power band as you. I did hit 70 MPH indicated today on a long steep downhill run at 6700 plus RPM but that doesn't count. My normal top speed is about 60 MPH indicated. No GPS to check speedometer.
She does seem to run out of juice at 5500 or so RPM.

axa,
Also saw 425 F on my cylinder head temperature gauge on a long steep up hill climb wide open throttle in 4th gear.
I eased off on the throttle and the CHT went down nicely.

Anyway, I had a nice ride on the Dragon today. She is running just fine.