I think the stock flywheel is 19 lbs, with the lighter ones being 16 lbs.

The heavier flywheel will help with stop and go traffic. But 3 lbs is not much difference. Some cars are able to knock over 10 lbs off their flywheel weight.

Supercharger? N2O or rear mount turbo seem like better choices. But they all have their advantages. I chose the cheapest of the 3, N20 for $1000. And that includes tuning and all the safety switches. But if $ wasn't a factor a rear mount turbo for $4,400 would be the way to go.