TD exhaust manifold/pipe gasket?

Has anyone tried to use the MGA/MGB round steel gaskets that fit between the bottom of the exhaust manifold and the exhaust pipe on a TD? I must have replaced the triangular gasket about 8-10 times over the years! Keeps blowing out in relatively short periods of time. Yes, both surfaces seem flat. I just thought that having a round gasket like that might help keep the gases contained and directed through the exhaust system. Even if the flange surfaces are perfectly flat you'll still have gasket failure if they don't align correctly with each other. That's difficult to accomplish when the exhaust manifold is clamped firmly to the engine and the lower end of the header pipe is clamped firmly to the chassis and the rest of the exhaust system. Have you tried loosening up the lower end of the header pipe to provide some give? Often that will let the flanges pull up tightly against each other. I'm not familiar with the MGA/B setup, but some older MG models use a round ring with the outer ...  more