The bject in modding isn't always chasing more rpm's. The important thing for us is torque. Top speed for most of the larger scooters is more than acceptable for most of us but getting there quicker is always a plus.
Open up the air boxes, upjet or step up the injector, and open up the exhaust, or bypass the EGR systems.
That will get the puppy breathing.
HPI or Accell or any number of suppliers make coils to light it all up. You can even use a coil pack form a Chevy Camaro or a Ford Mustang. Maybe 3 extra HP, and an equal torque increase for well under 100.00 bucks.