The biggest update was around 2017. The original models are ride-by-wire but run cables from the twist grip to the control unit under the tank, the later models are full ride by wire direct from the twist grip. The switch gear was also updated on the later models, the main benefit being moving the much easier to operate cruise control button to the left hand side and being able to adjust it without disconnecting and starting all over again on the earlier models. The older models you have to hold the throttle at the speed you want and push the button on the righthand switch block to set it, without moving the throttle. To adjust the speed you have to disconnect and start all over again

. Also an air pump (I think that what it's called) was added to the header pipes for emission reasons. There was one updated to fueling map for the earlier models, but you can the whole hog with Todd's fueling modifications on this site, giving big increases in power and torque.