German, your comment is not at all helpful
Whizzwheels, I do not know too much about the Jab engines ito of getting more horses from them, however, blue printing seems to be a faily common option - although, I have no idea how much more power you will get. A friend of mine had it done to his engine, and the increase in power was enough to require that he got a coarser prop. The Jab factory down in the George area do this, so maybe give them a call, and the same applies to carb icing, I am sure they will have the answer.
Do not believe anyone who tells you Rotax do not suffer from carb icing, I can verify this from experience in my Bushbaby, although with the typical configuration where the engine is enclosed in a cowl, the air intakes sit up close to the fire wall which typically has hotter than ambient air, but under the right, or wrong conditions, it can occur.