bigger front tooth sprocket and 22'' tires isnt going to help you in a race but maybe it will in top speed. it will take you a little while to get there... i would stick with the stock gearing and run some 20'' tires for quicker acceleration. unless she is kinds slow on the 400 she is going to have you beat still. i have a few friends with ltz400's and they are pretty quick, even faster than the 400ex. I was running 240 kit with a few other mods to keep up with the ltz and unless he missed a shift or something he had me beat...