If you are a racer and have an LBZ-LML 6.6L Duramax, Gale Banks Engineering offers The best cast Duramax manifold ever. Lay the power down with Banks Big Hoss Duramax Exhaust Manifolds! For high performance, getting the exhaust gasses out of an engine is just as important as getting air into it. These race-ready, high-flow manifolds were designed by Banks for the ultimate in fit and performance.