Udi,

This may be as far as power is concerned, but Rossi engine cannot be adjusted as well for idle, mid-range and response.
So much so, that MVVS makes a carburettor especially for Rossi engines.
It is much cheaper than the Rossi part and is a 'drop in' replacement.

It gives Rossis excellent speed control and response (not like MVVS yet), as well as a 200 RPM boost on top.