Main Material: 304 Stainless Steel. Stainless steel 11-gauge .120-inch wall, 2-inch OD Up-Pipes. OEM upper exhaust pipes on both the left and right sides. Enhances the overall durability and corrosion resistance, but also contributes to an improved turbine response speed. Lower exhaust temperatures mean your vehicle runs more efficiently and lasts longer. For 2001-2016 Chevrolet GMC LML 6.6L Duramax LB7 LLY LBZ LMM LML Diesel.