You can go down a size on the front sprocket, or up a size on the rear sprocket - either one will cost you a little top speed, both would work too, but if you are going to put that much effort into it, my suggestion would be a performance exhaust - that would probably be the most effort and cost-effective method.
For Tomos/Puch you want a Bi-Turbo two-piece, and for some others I think LeoVinci makes decent ones.
If you have a Tomos, you can also do this for some immediate (tho very minor) improvement - near the end of the exhaust is this tiny little screw...unscrew it, and pull the entire baffle out, it will change the exhaust note slightly and improve performance just a smidgeon, but it'll do till you get something better - and I happen to think the alternative exhaust note sounds pretty neat.
As for the jerks behind you, simply begin the arm signal for a right turn and present one finger extended in that universal gesture of communication between bikers and four wheelers...
-Ree