I had a Fidanza lightened flywheel on my Miata. After first installing it my reaction was
Completey changed the whole experience. I kicked myself for not doing it sooner until I remembered its a big job that should only be done when the cluthc was replaced. Best bang for the buck from a maintenance job for sure.
But with its greatly reduced weight came ALLOT more noise. I could actually hear it spinning and the car was noisy to begin with! Very visceral, I loved it.
Some people didn't care for all the racket and complained that they felt like they were in a tin can.
Like most mechanical mods I recommed finding soemone with who has the mod already and going for a ride. Otherwise its an expensive roll of the dice. I learned this lesson with suspension mods in a big way.