What do you have for a budget? You can do the cam mod, pipe, filter, jet (on a dyno), change to a kick starte (loose weight). If you want to spend money, you can change cams, port polish, bore, high compression piston, ice cube kit, valve job, valve springs, ect... What do you want to spend depends on what you get (I know you already know that though lol).
If you are willing to spend some bucks call Mark Hargrove at www.kenzcycletech.com they do great work.
hope it was ok to post that link?