Ditch your leaking factory exhaust manifold gaskets in your 6.6L GM Duramax and replace them with the PPE High Performance Exhaust Manifold Gaskets. These gaskets feature a multi-layered 301 stainless steel construction and are designed to work with PPE High Flow Exhaust Manifolds or GM OEM manifolds. Also, these gaskets feature an oversized port size(46.8mm x 41.0mm) for maximum exhaust flow. Sold as a pair.