As long as you maintain your machine you will get the longest top-end possible. Clean your air Filter regularly, have your bike jetted correctly, mixe the gas +oil correctly, adjust airscrews, and clean out your carbs from time to time you will be fine. My 01 has the factory topend in it, and the compression was checked last weekend at 120 psi and it was about 122 in each cylinder last fall , starts on 1 kick and pulls like a rocket.