I race a box stock 2007 YZF450 . It runs great ,the only thing that i have done to it is put a pro circiut fuel mixture screw in the carb . I want to race it at loretta's in 2010 in the senior 45+ & senior 40+ classes . Before then I was thinking about getting some engine & suspension work done . I don't know where to start when it comes to the four stroke engines . Here are the companies that I was concidering on the engine work : Pro circiut, DR.D,Reynard Modifications ,FMF . Here are the ones concidered for the suspension : Pro circiut , Ohlins ,Reynard Mods , Race Tech . Thank you all for your input in advance !