Well if you plan to race, you gotta go with the 300EX... being only 13 its a very good quad, and you shouldnt grow out of it too soon. if you ever do the 300 has alot of potential. you can put some money into the motor and shocks, and get it to beat almost any bigger quad

 

There is not much speed diff between all three really. The 250ex is not a true sport quad....it's auto clutch and shaft drive which means it is really realiable, but for racing 300 ex.