Cosworth Pistons, Honda NC-30 & NC-35Pistons are the single most important component to making power. I piston that does not seal, loses power. A piston that has a poor dome design will not have good combustion. A piston that rocks significantly will cause excessive friction, and lose ring deal. And, a heavy piston will damage the rod bearings, main bearings and wrist pins. There are even more considerations that must be taken into account when designing a high performance piston.