I guess getting the exhaust headers out can sometimes produce enedpected results! I could see the stud turning with the not and thought 'Oh Oh! - it's going to shear the stud and it's going to be expensive!' But the nut and the stud kept turning and I got the lot out!

I now don't know whether to try and remove the studs on the other sideand use stainless mushroom bolts or to go with a brass nut/bar arrangement and stay with steel studs. It's be silly to have one system on one header and something else of the other. Mmm more decisions.