ICS Aluminum Piston
The ICS Aluminum piston is much stronger than stock pistons and is designed for heavily upgraded guns. Aluminum pistons are much stronger than polycarb pistons but they also don't have as much forgiveness. To go along with a good aluminum piston you should also have a good set of gears, and they must be shimmed very well to avoid premature and uneven wear, and to avoid excess gearbox noise. Since Aluminum is heavier than polycarb it is highly recommended to upgrade stock gearbox shells to reinforced ones.