I have to say that if someone have money to spend and don't know where, is a very good to buy a lightweigt flywheel.
The difference is very noticeable from the good side. Espesially on my car that have the pot type flywheel.
The Fidanza flywheel that I fitted is also a pot type, and goes straigt on c20xe engines with pot type flywheels, and also on c20let engines.
The code is 188021 or (vx8021) from helix and it weights 4,2 kg.
The idle is stable, the engine starts easier, the engine revs very fast, and you feel the difference in all gears. Even in 4rt&5th gear. But on 1st and 2nd gear the difference is very noticeable. And when I say very noticeable I mean like the engine have +10 bhp. I know that maybe this I said is not correct, but that is the feeling.
Also it isn't more difficult to drive the car, and the rpm's drop faster when you have gear but the difference is very small. I don't think that someone will see a difference when he go a travel with 5th gear.
And last that I noticed and the most important, is that the engine don't loose nothing on high end torque. It always go faster up to the rev limiter that it sounds better!