Forged pistons are always considered an upgrade to cast and hypereutectic pistons. They are created from a billet of extruded aluminum alloy. This billet is compressed into heavy forging dies that create the rough shape of the piston—the piston blank. But, since the die is made from two mirrored halves, this eliminates the possibility of designing the internal area in the raw forging. This denser, more ductile material means that a forged piston is inherently stronger and more forgiving when its limits are exceeded. There are also different alloys used in forged pistons. The most common alloys are 2618 (a low-silicon aluminum), and 4032 (an alloy with around 11-percent silicon).