First off, they use a forged process when creating their pistons, which results in a much stronger metal. Not only that, but they use a 2618 aluminum alloy which is much stronger than stock, can handle large amounts of boost and ignition timing, and has minimal expansion.
They have also moved the first ring groove farther down on the piston to give a thicker, stronger piston top. Then to top it off (pun intended), they offer an optional ceramic thermal coating on the piston tops which reflects the heat and reduces heat soak on the pistons and the piston skirts are moly coated for scuff resistance.