Are these worth getting and which one is recommended? There are 11 lb flywheels, 8.5 lbs, etc. Is there any brand that's better? A.C.T. or Fidanza, and what will it do for my civic?

ACT is a great company, i've never heard of Fidanza so I have no idea... it will reduce weight of the flywheel increasing hp. Its like the difference between heavy wheels and lightweight wheels. gains of maybe 10hp, depends on the setup.

Yeah but what weight flywheel should I go with, and is too light not good. I've heard if the flywheel is too light then you will just be high-reving your engine too much, and not help much in power gains

the lightened flywheel will allow you to rev faster (if that makes sence). you'd be able to reach your shift points before the next guy.

Will reving faster and speeding up the shift points equate to faster 0-60 times or 1/4 mile times?

yeah a lightened flywheel will make a huge difference. id say go between 8-9 lbs. you can get them lighter, but then you will notice that in downshifting to slow your car, it will not slow you as fast. also, any lighter and in normal street use, you will chance warping it. i think im going with an 8# or 8.8#, though ive found them as low as 5#, and they say its ok for street use. but too light can feel weird on the road.

if you're going with a few minor mods stick with a 12 lb flywheel. If you're going for an all out complete buildup, go for a 7.5-9 lb flywheel.

ACT makes a good flywheel.