Here is the engine Ghost is talking about, the UCTKAM 2.5 (translation, CSTKAM) and they often come with a tuned pipe.

If you find a new one on the web make sure you strip and clean it. Be especially careful of the screws, they are fragile and shear their heads off with great ease if you are ham fisted. Also, the head appears to be drilled in situ for the mounting screws, the screws have a difficult time lining up if you change the orientation.

Luke.