what about the clutch are you not happy with? the lever pull? if so, check out aftermarket slave cylinders by evoluzion, yoyodyne, stm. looking into a radial master cylinder's not a bad idea as well.
if the clutch pack's kinda on it's way out, look into getting a barnett stack. comes with some stiffer springs in addition to the friction and driven disks.
if you want to cut some weight, yoyodyne's got a lightweight clutch kit for a reasonable amount of $$$ that's pretty sweet. motowheels also has a bunch of options but i've no personal experience with their clutch kits. a lightweight kit will allow the engine to rev a bit more freely because of less rotating mass. similar to the effects of a lightweight flywheel.
finally... there's also the option of getting a slipper clutch. they're typically lighter than the stock clutch assembly and they have a mechanism that allows the clutch to "slip" if you're not matching revs when downshifting. this helps prevent the rear wheel from locking up. personally... i match revs fairly well and haven't had a problem yet...