don't listen to idiots like orangerobin. it is a lot more fun and rewarding going as fast as you can on your stock parts. he obviously lacks the skills to tune, so he thinks spending money on a kit is the only way to go.
if you want speed out of your vespa, you should throw away that horrible polini pipe and get something better, cut your crank and open your intake and port away!
also, you already lightened your variator and weights, but try running with only three weights and see what that gets you. it helped out with my 50cc bravo a lot.