[Gaz64]

You should take the weight of the clutch into account when selecting a flywheel weight.

If your stock flywheel is 30lbs and your clutch in 10-15 lbs, then halving the weight of the flywheel doesn't have that much impact.

I ran a billet steel flywheel (2.7kg) in a 700kg street car.

My V8 weighs 2900lbs, and runs a 18.5lb steel flywheel, sprung centre single disc clutch, T5 5 speed, 3.5 diff gears, 245@.050 cam. Easy to drive