you should be able to do it with the pipe on. i never needed to remove it. it can be tricky to do. i usually will use some sticky gasket sealer to hold the gasket to the valve cover because some times you will hit the rocker arm and knock it off and it will leak out the back and not even know it. till its to late. they make stuff called felpro-bond. or i use the old shellac gasket sealer.
