Not much, and it depends!! :)

If you want really sharp throttle response, then the lightened flywheel is for you, or if you just have to have every available extra, then it's for you!

Ultimately, with less weight to spin, the crank can get on with its' job of turning reciprocal motion (up-down of the pistons) into rotational motion and spin the clutch/transmission, but as a consequence of this, less weight means a loss of inertia on inclines and a therefore a slight drop in torque.

If you're racing you probably want it!

Andy.
NSR-WORLD.COM