Pistons and rings operate in a very explosive environment, so they have to be extremely tough. GM Performance Parts are designed to withstand the rigors of high-performance engines. The pistons are factory-tested for quality assurance. GM Performance Parts pistons are sold in a variety of sizes and compression ratios. There are pistons for GM Big-Block engines ranging in displacement from 427 cubic inches to 572 cubic inches. Pistons are sold individually and are fitted with wrist pins.