Upgrade engine and pistons

I think most modern non-turbo cars come with cast aluminum pistons and compression around 9.5:1, so shouldn't be a problem. Slant pistons appear more rugged than most current designs. They changed to short, stubby pistons with minimal skirts and top rings further up to minimize drag and quenching. Forged pistons require more clearance since the metal expands more, and consequently have more piston slap and such. They aren't the best choice in a daily driver.