What kind of ignition circuit does you scooter have now? I doubt that it has any rev limit, rev limit is usually due to intake and exhaust port size and muffler back pressure. Some work on the ports might be more useful than a new ignition system.
my stock cdi has an big ic inside called cpu that control the ignition or spark at high revolution. my plan is to make a custom one(transistorized)
but i have only a few idea on building one.