John
The old 427 Ford medium riser , high riser, tunnel port and SOHC engines used the bolt through the cap design rather than the stud and nut design.

This is a much stronger setup with less likelyhood of a failed bolt.

Cost more to produce though as the cap has to have the little dowel rings to pilot it (or some method)

Many great ideas simply fall by the wayside in favor of cost savings.

Its great to see AMG/GEP using some of these very sound engineering principles.

Robyn