Originally Posted by mike saunders
Heavier flywheel = more rotating mass = more drivetrain loss = slower time to build speed. A heavy flywheel would help if you revved the crap out of the car during a standing start, but the additional mass likely puts additional stress on the clutch.
The major immediate downside to a lightened flywheel is the mental and physical adjustment that the driver needs to make to compensate for the difference in clutch engagement. I stalled out a few times when I made the switch...
the heavier flywheel would only be helpful if i had a v8. over all the less weight the less stress, and the better off i am.