Wiseco's are forged therefore the metal structure is much more dense which allows for a thinner wall to maintain the same strength but needs less material or its lighter for the same strength. Art, Pro-x, OEM are cast hypereutectic pistons. Hypereutectic means it has a 16% silicon content for strength and durability, also a Hyper*** pistons thermal expansion rate is less than a forged pistons expansion rate . You could think of it as in a cast piston the molecules are father away from each other so it takes more heat to make them move away. Wiseco's are not as hard as their cast counterparts, you can see this when they stick. A forged pistons molecules are hammered real close to each other, stronger yes but will expand more. Wiseco's are ok depending on how they are set up and for what and how they are used. You really don't need to balance the pistons they come close enough for most aps. What really matters is what is the application and how everything is set up.
