hey milonaar, I am 17 now I was in your same spot last year just trying to get a old x2 runnning lol. So this winter I had the money to buy another dirt bike or redo my x2, So I conquered my goal of building my dream x2, now 200hrs later I have a killer x2. I couldn't be happier with my x2. On the inside I did a sp 750 bored to a 768 freestyle ported, lightend and trued pistons, lightend 650 fly wheel and electronics, ada head with 175 psi, factory limited 750 pipe, jet craft silencer, carbon fiber reinforced inside.
http://www.x-h2o.com/threads/102539-winter-x2-build this is the link to my build. Glad to see someone else my age be on a x2!