Long ago there was a German who got something like 127 hp out of one of these engines, but it was rebuilt from top to bottom. New cams, seems to me new pistons, pipes, exhaust, etc. It today would be still massively short of a current KTM 1290 or other new bike.That is pretty much my reasoning too It is about rideabiliy really, I had heard people claiming 20bhp after a reflash but to me, you don’t get that kind of power out of a normally aspirated engine without doing a whole lot more expensive stuff to the internals.
As you're now aware the Flash remaps throttle response and can remove some restrictions.