Before you do ANYTHING, read Fred's guide. Upgrading will probably decrease the engine life, especially with speed kits that push the bike to the limit.
REad up and be wise about what you do. Your probably better off getting a Puch or Tomos, retrofitting it with a "tuned" pipe, cleaning the carb, and doing an all around tune up on the thing. You should be able to get at least 35 out of just about any Puch or Tomos in good shape and running order.
Let me know how it goes... be wise with your $$, for yours, and the moped's sake.