For those seeking more power, upgrading the restrictive factory downpipes on your 2001-2004 GM 6.6L Duramax should be a priority. Our downpipe kits provide an easy way to give your 2500HD/3500HD a more aggressive exhaust note while increasing horsepower, torque, and fuel efficiency. These kits also help lower EGTs, keeping your truck's temperatures in check during high-performance driving. Browse our full selection of downpipes to find the perfect fit for your GM truck and confidently showcase your performance upgrades. Pair your high-performing downpipe with our selection of Single-Exit Exhaust or Dual-Exit Exhaust. GM Duramax Fitments: 2001, 2002, 2003, 2004 GM 6.6L Duramax.Submodel Fitments: WT, Custom, LT, LTZ, High Country, 1LT, 2LT, Pro, SLE, SLT, AT4, Denali.Some exceptions apply, please see individual product pages for specific fitments.