^^That, and it'll rev safer at high speeds.
That and a billet connecting rod will allow you to remove the governor and upgrade the valve spings, so that way you can rev you engine upwards of 6K RPM safely, without the risk of having a Predator 212cc grenade between your legs!
Well, the billet flywheels have an 8 degree timing advance over stock iirc (32 degrees instead of 24), so it'll rev better up top, but you loose some torque down low, which will make it a bit slower off the line. If you want to play around with the timing on a billet flywheel, get some timing advance keys and install them backwards, so it retards the timing. I'd say a 2 or 4 degree retard with a billet flywheel should keep some bottom end while improving top end (= 30 degree advance with a 2 degree key, 28 degree with a 4 degree key). Remember, rotating the flywheel clockwise advances the timing, rotating it counter clockwise retards it. Also, more timing (advance) helps top end, but it'll make the engine idle higher.