Replace or upgrade the exhaust system on your 2001-2004 Chevy/GMC 6.6L LB7 Duramax with a new downpipe. The stock downpipe often features bends or crimps in the tubing that restricts the flow of exhaust. Aftermarket downpipes offer smooth mandrel bends and larger diameter tubing for an increase in horsepower and torque and can help your lower exhaust gas temperatures (EGT's). You can find all the top brands including AFE, AP Emissions Technologies, Banks Power, BD-Power, Dorman, Fleece, PPE, Magnaflow, MBRP, and more!