Reducing the rotational mass of the engine gives improved engine response, it can pick up or lose revs quicker, meaning faster acceleration and more engine braking. In the past, weight was removed from the standard flywheel. Years of clutch abuse, heat and revs may push this into an unsafe condition. The answer is to use a new steel flywheel. A standard cast iron flywheel weighs 10-16 kg, our steel versions weigh about 4 kg.