Hey Prince,
The ultra-light flywheel weighs about 12 ounces, the stock one weighs about as much as Minnesota.
Dave did some testing early on and found a noticeable drop in 0-60 times. On the other hand, DBM noticed an increase in time in 80-100.
Lighter flywheel means it spins up faster, has more engine braking, and will make the bike slightly easier to change direction (see ‘Physics 101’).
Getting the old one off is easy if you have an impact gun and a flywheel puller. Going back on requires a holder to clamp the tiny flywheel, as the bolt holes are no more.
Dave has a rental package for the tools needed.
Not sure if he has any left. I have one ultra-light.