On the 03 you may want to drill your slides to help get rid of the throttle hesitation and the airbox and exhaust mods do help with the things you mention. This being said I would like stated above do all the standard maintenance first and check to be sure you don't have any vacume leaks and the fuel filter is clean. The chatter shouldn't be there in the clutch. My clutch and Wendys for that matter are very smooth. Be sure you have the right kind of oil in there and enough of it. You may have hardened spots on the clutch plates and some warpage due to an inexperienced rider slipping it too much, could also be extremely uneven spring tension. If you decide to pull the cover and check be sure you buy a new gasket as I hear that one is not reusable.

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