Exhaust manifold - studs or bolts?

[keynsham1]

I have a new exhaust to fit to my 1.9DG. My old one was very rusty but having removed it I was surprised how thick the pipework is. On reflection, most of it was probably OK. You live and learn I suppose! It all came off fine except for one bolt in the exhaust port which sheared off its head. I have two ports with studs and two with bolts. That seems odd but I suspect it isn't the first exhaust it has ever had. I am planning to refit the new exhaust with studs as I prefer them. Are they supposed to be studs all round? It seems odd to have a mix!

[itchyfeet]

Early exhausts have bolts in some locations I think because the pipe bends too close to the hole to easily use a nut.
Late exhaust is studs all round.

[shepster]

Also if they were all studs once it's been on a while and the joints 'weld' together you would have to cut it off.