well im only 16 and i can see it was pointles in putting a cat in the exaughst of a 2 stoke bike i mean my bike is a 04 plate and when i cut it out (april 2006) it was so gunged up and there is no way of changing cat as the exaughst is a seald unit ( maby a ploy to get mony off people ) but yer my bike is so much better and sounds like a poper 50cc so crisp like a motocross bike