have a search for DIY head porting on the net. Provided you have some idea what your doing its quite possible to achieve a bit of hp out of this for not much cost. mate of mine did it to his scooter a while back, and it went heaps better... (too bad he bent the frame on it doing jumps...)

being a 2 stroke it would probably take to a nice expansion chamber on the exhaust if it doesn't have one already.

Have a play with the jetting. see if you can drill out the jets or something. Make sure you do your research first though, and don't wreck it.