so I'm hearing from this experience - the bolt thread is softer than the manifold...hence sacrifice a bolt rather than a manifold - makes sense - just never seen it in practice. And I never wanted to find out either....
.....although I did almost the other day - my mates torque wrench had a different sanp so I wound past the click ...hmmm...that's awfully tight ...hmmm.....better go and check this baby....sure enough it had the softest click you ever felt......I qucikly went back and dewound that bolt.