The conversation about piston material is an attempt to source the correct piston design/material for a specific application.
4032 is generally better for cast irons liners because the high silicon content lowers the expansion coefficient. Full circle skirts will often create a quieter cold engine.
The quest about density differences is simply an excellent way to reshape pistons with having to CC each process. 4032 and 2618 are different enough to require a different formula to calculate CC based on weight.
After machining it makes sense to CC the final product.
