Hardened head bolt washers are used on all our engines. While these do cost more than normal original plain steel washers, they do not get grooves cut into them from the underside of the head bolt plus these washers do not cup. What this means is that an even clamp load is applied through to the head gasket surface and in many cases what others think they are experiencing with head gaskets settling is actually these parts failing.
We use high quality stainless steel hardware with the head markings removed. Original cadmium fastenings can be used as an option.