On the set of Dutra’s on the slant on my D150. Between the cylinder head and the Dutra’s I have not had any issues using a stock Felpro gasket. I did have the machine shop take a very light skim cut on the manifold face of the head so it is clean and flat. However from the Dutra’s exhaust exit to the flanges on the exhaust pipes, over the counter two bolt bolt gaskets do not last. They will be good for a couple of thousand miles then burn through and develop an annoying exhaust leak. After changing those out the second time I put in a Remflex two bolt hole gasket and it has been fine for over 35K miles. It’s either the exhaust exit on the Dutra’s or the flanges on the exhaust pipes that have an issue but the Remflex gaskets handle it.
