I do not think that the manifold corrosion is directly related to the bonding system. Copper will eventually fail in a salt-water environment, which is what I experienced.
You can verify the problems with copper by inspecting some of the original wiring in the boat, which was not tinned unfortunately. The copper strands turn black.
In the case of the manifold, you have trapped raw water inside and you cannot see the gradual corrosion taking place.
Phantom, A54 #44