Yes the exhaust arrangement isnt great and I had a few gasket failures but always from an exhaust to the exterior so you can see and hear the leak. The distance is much greater between the exhaust and intake ports so a failure there is much more unlikely and Ive certainly never seen that. However in the end the solution was simple - just keep the manifold fixings tight and since including that in my routine maintenance Ive never had any more porblems...