My 940T exhaust manifold gaskets are lasting only about a year before blowing out in various places. I use OEM Volvo Set (p/n 271704) and maintain the proper torque.
I have 2 questions:
1) Is if there is a better brand gasket to use?
2) Should I consider having the manifold machined by a shop to ensure the contact face to the cylinder head is true?
Beyond using OEM studs, nuts and gaskets per the FAQ Section, and maintaining proper torque, I don't know how to make these gaskets last any longer than about a year.
BTW, there are no obstructions in the exhaust system or catalytic converter. These have all been replaced within the last year and do not cause any back-pressure issues.
Thanks everyone!

2 other thoughts come to mind. there is a somewhat hidden bracket which affixes the manifold to the engine block. is this attached?

and are the 4 cylinder head exhaust port surfaces true flat one to the other?

Well, 2 more things to check when the job gets underway. The L bracket under the manifold is in place properly.
Per the FAQ, I'll also take the time to replace the oil filter housing extention and cooler sealing rings.

2) Should I consider having the manifold machined by a shop to ensure the contact face to the cylinder head is true?

turbo manifolds are thin and notoriously weak under the relentless heat from that setup. you might very well have a manifold which if you place a machine shop straight edge across its 4 mating surfaces come to discover small gaps from true flat in 1 or more.