http://www.mopedarmy.com/wiki/Puch_horsepower_differences
I would start with a pipe, since you're going to want that if/when you kit it anyway. The 14mm carb will help you, but make sure you upjet it when you install the pipe. That should get you somewhere in the realm of 35. If you want to go faster after that, you could do the kit as a second installment, and if you want to go faster after that, a larger carb would probably help. Different people will tell you different things, though.