Evo X Flywheels
Scientifically speaking, a flywheel is there to store rotational (kinetic) energy and to smooth out the delivery of that power. The heavier the flywheel, the harder it is to get spinning but the more energy it stores. Lighter flywheels spin up faster but don't keep the energy around as well. Depending on how you drive your car, you may prefer a heavier or lighter flywheel to match.