These cylinder heads have been refurbished with new guides and Wrightwood Racing Teflon valve stem seals and have been refaced by 0.25mm (0.010 in) for a perfect seal to the cylinders. Ether run them as they are for a slightly improved compression or use the factory thicker cylinder base shims to make up for the 0.25mm they have been shaved. All studs/ hardware have been re-plated with Zinc-yellow Trivalent Chromate or replaced as needed as shown in the photos. Please check out the photos closely. These are very decent heads with minimum pitting in the combustion chambers and the ports look very good. Porsche part number for each head is…