I think this overrange is specially for a Minaralli short crankcase, So no modifications has to be done Although a overrange for a long crankcase will not fit, unless the crankcase cover has modified, but this is not good for the stiffness of the crankcase.
it may take sometime, in the near future the chrome plating might chip off because of very hot exhaust. it will start at the flange/header/elbow part..