Quote from sam93 :

Speedfights aren't a heap, my mate 04 speedfight 2 goes just under 70mph, but it has had a bit of money spent on tuning parts for it, for example, bigger piston kit, malossi big bore etc. Haven't riden a scooter what has had as strong powerband as what that has. Scooters don't intrest me though, if I was you I would go for a RS50, may be more expensive then the others but they are worth it, just ride before you buy because they have most likely been ragged around, better off getting a 1 year old used RS50. If you dont wont to get a car when you are 17 I would get a DT125 because they are good bikes and you can make them go quick.

Didn't read the bit about you got the bike, anyway good luck with the TZR, not as good as the RS's performance wise but if you like it, stick with it, if you are going to change the exhaust and that, the 2 things people go for is a big bore and an exhaust. A good brand for big bore kits are Malossi and a good brand for exhausts are Arrow.

just buy bysicle and say its a moped? i think even bike is more fun to drive. or, buy a piikkinen(125cc motocross bike, we say its piikkinen in finland) and fill the exhaust muffiler. then it sounds like a moped but it goes pretty fast. if cops come, press some gas and get to enduro lines in forest, of course if you live in a big city you should not to buy a 125cc and say its moped