Your 6.6L Duramax engine produces high exhaust temperatures and pressure that can eventually cause factory up pipes to fail. Replace your factory up pipes with these High Flow Replacement Up-Pipes from PPE. PPE has taken OEM replacement to a new level. These up pipes allow 53% greater flow than stock and are a direct bolt-on to your factory manifolds. But unlike factory parts, PPE Up-Pipes are manufactured from 11 gauge 304 stainless steel and include our superior 304 stainless steel, internally-sleeved bellows that can take the abuse of high temperature and high pressure.