A few months ago I finally (after 4 tries) got my manifold set to not leak by following directions recently posted here (including torque wrench use) and using copper high temp gasket sealant between manifolds and on the exhaust manifold to gasket. Well, it lasted about 6 weeks. I'm going to remove the entire thing yet again, bolt the manifolds together with a new gasket and take them down to the machine shop. Estimated cost $60 but I should have done this to begin with. Next time.