From Jeff240sx

...here is the cold, hard truth about the effects of a flywheel.

Effective weight =
.5 flywheel weight x ((FlywheelRadius x Gear x FinalDrive)/(TireRadius))^2
So. Lets plug in numbers.
Our flywheels are what, 220mm or so. That's 8.66". Lets use that. Stock flywheels weigh what? Lets us 22 pounds, cuz some guy said 21-23. A Fidanza weighs 11, right? Finally, the tire is 24 inches, at 16" alloys, 205/50/16.
1st Gear:
5.5lbs x ((4.33" x 3.32 x 4.08)/(12"))^2 =

131 lbs lighter.
2nd gear = 43 lbs lighter
3rd gear = 20 lbs lighter
4th gear = almost 12 lbs lighter
5th gear = 6.8 lbs lighter.

-Jeff