I talked with a local dirtbike performance shop here in Michigan about doing the YZ exhaust timing for me. They claim that it is already YZ timed. When doing a bike like mine (2001)when they moved the cam they discovered that there could be valve to piston interference. Does anyone know for sure that after model year 20XX, WR426's were YZ timed at the factory? ------------------------ Most standard mods (grey wire did nothing for my bike), 1 less tooth on front sprocket (great for tight trails, raised fork tubes 5mm, rear wheelbase shortened 1 link, Baja designs street legal,Brush guards with turn signals, Scotts dampner, Devol radiator guards, 1" higher Renthal bars, Clarke tank with YZ style seat,front disc guards, frame boot rub guards, Speedometer, Bugeyz mirror on helmet, Helmet cam, Air freshner (just kidding about that one.