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.