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For all it does well, one of the stock LS7's few quirks is its hypereutectic pistons. Mast steps it up a notch with forged Mahle slugs and matches them up with Callies/Compstar 6.125-inch steel H-beam rods. The pistons feature Mahle's Grafal coating on the skirt surfaces, which reduces friction and increases scuffing resistance. It also allows for running a tighter piston-to-wall clearance for reduced blow-by and piston slap. With -3cc valve reliefs, the pistons yield an 11.7:1 compression ratio.