Hey Kurt,
What exhaust did you get? And what weight rollers did you use? Is your S9 liquid-cooled or air-cooled?
Some (fairly) easy mods you could do would be to install a Malossi variator and, if you have a lot of hills in your area, a Malossi torque drive.
Are you in the UK? I'm not sure what the laws are these days (I've been out of the country for the past ten years!) but later on you might want to install a 72cc big bore kit, bigger carb, and air filter.