super unleaded 97RON

[Dead Eye]

Agreed, the FZS 600 shouldn't have any real improvement because of the carburettors - you might be able to get a it of an improvement if you had it dyno'd to use the higher octane fuel. Having said that, I do use it in my bike. If nothing else, it does prevent premature detonation in the chamber.

In my car however, which is fuel injected, I've gotten about 15-20% improvement on MPG (from 24~ to 30~)

Also, some people recommend Kerosene (airline grade fuel) for cleaning out the fuel system a bit so I guess the higher octane might assist in that as well? Not significantly mind you...