Flywheels provide rotational inertia to the engine, Lightening the flywheel reduces the rotational inertia and enables the car to pick and drop revs faster which can be very beneficial in certain applications and detrimental to others. Lightening the stock flywheel we are limited by the amount of weigh that can be taken off and one does not know how much strength is compromised until tested. With forged aluminum flywheels such as Fidanza, we are able to cut the weight to below half in certain applications without sacrificing strength.