Mal, the only restriction “by design” on a moto-x motor is the intake track is turned to ovoid the rear shock. That was eliminated with the cut cases and straight intake boots.
The later RS’s design benefits from a balance shaft, and programmable ignition that’s where a lot of hidden power comes from, and from what I see with respect to the KZ’s, that’s not allowed, and or implemented…
And again…. If you could have 75hp in a KZ package that would great, but they are designed to run around a 1/2 sprint track, so they have to be drivable also… That’s kind of what happen to 2 stroke MX bikes, they make more power for the size, but the 4 strokes have a better power band, which equals faster laps, which equals wins…
CR