Paul W's Bullet sounded pretty crisp to me, the 5 speed really was working well to keep him "on the cam". You can hustle along smartly on 23-25 HP with proper ratios. My old bone-stock 1978? XT250 Yamaha ran 65-70 pretty reliably on flat ground, no headwind. The big gap between 3rd & 4th on the 4 speed drops my 500 I.B. noticeably "off the cam". The 5 speed has better ratios to work with. These engines seem capable of 6000 RPM, maybe not as a steady diet, but Paul W had room for more. For max speed the gearing needs put the max HP where it can balance the drag. Many have gone 100 MPH on 30 HP, proper gearing & rider blended into the paint.
My speedometer is temperature dependent - at under 55F keeping up with local traffic I show 60-65 MPH. A bit later in the day at 65F, the same traffic is 50-55 MPH...Obviously I am much speedier in the AM! Or the grease dragging the magnetic cup around in the speedo is grippier when cold...
In any event, the Bullet speedo is more entertaining than informative.