Besides its beefier construction, the 5.8 piston bowl volume was filled in from the 5.4's 13.2 cc to 10.3 cc. That, along with the bore increase, raised the compression ratio from 8.4 to 9.0:1 in order to improve off-boost fuel economy. Also visible are the moly anti-friction coating on the skirt and the new 5.8 ring pack. Looking to offset every gram possible from the increased piston weight, along with reducing friction, supporting the 7,000-rpm over-rev, and mating with the cylinder wall finish, Brendan Vido went from cast-iron to reduced-tension chromed steel on the compression rings and carried over the oil control rings. The steel rings are lighter, moving the total ring package weight from 26.4 to 23.3 grams. And that moly patch earns its keep considering the 5.8's piston-to-cylinder wall clearance is a scant 45 microns or 0.0017 inch.