If you go to the site chinariders.com you will find a lot more info on tuning the xp. the word is you can bump it from 15hp to about 18 or 19. I've had one for 2 months and really enjoy it. The only mod I've made is changing the rear sprocket to 44 teeth (stock is 48). I haven't tried to get top speed out of it but i'm only turning 6000rpm's now at 55mph. it cruises much nicer and the low end is still good for trail riding. Oh, I'm also getting 90mpg now. Good luck!