Always replace the gasket after inspecting or replacing exhaust manifolds and risers Sierra gaskets are engineered to meet or exceed manufacturer specifications and provide added value to boaters and marine mechanics. Exhaust manifolds and risers take a beating in the marine environment and require regular inspection to avoid catastrophic engine failure. After an inspection (or replacement) it is equally important to replace the manifold and riser gaskets to maintain separation of exhaust and cooling channels. Sierra manifold gaskets are designed to perfectly match exhaust and cooling ports and give mechanics the confidence that the job is done right the first time. See our Engine Parts Selector to confirm which gasket is correct for you application.