You can say that the root cause of the manifold cracking problems is that the manifold seeks to expand with heat, but it is restrained from expanding from the rigid cylinder head.
The conflict between both parts is resolved with cracking...
I have bellows on my own car:http://www.fiero.nl/forum/F...L/142133-3.html#p111
The intent of the bellows is to allow each part of the manifold to expand freely with the heat, stress-free (well, not completely free of stress, but far reduced).
Only a few thousand kilometres so far, so I cannot say that bellows are the final solution to 2.8 manifold problems, but so far things are looking good.
[This message has been edited by pmbrunelle (edited 08-02-2020).]