how many of you who have commented actualy have one??? lol
i do
i have the billet 3.1kilo from atspeed £235delivered before you ask
i fit one to my fast road car (used once a month for trackdays) to compliment a new valeo clutch (£95) as my standard flywheel was worn.
they are not hard to drive about in traffic etc.
they do not slow you down when going up hills.
they do give better throttle responce.
no extra power to be gained.
they do make your car idle worse if it isnt perfect to begin with.
you do not need to balance the standard fly when balanced lightend.
and lastly if you do have your standard flywheel lightened then 1kilo will be the max to safely remove. hardly worth doing.
back to the original question. not much difference at all.