Carbon, Oil And Engine Life
Head gaskets are under a lot of pressure, and are known to fail. Just looking at the DD15 gasket you can see the durability, and the additional sealing. This doesn’t look like a gasket that will give trouble. The gasket is two ply and is riveted at the sealing grommets to maintain torque load. The gasket does not include a compression ring at the centre of each cylinder, further enhancing durability.
You can also see the carbon scraper ring in this picture here, more on that later.