Find multiple Exhaust Adapters for the custom exhaust on your 2004.5-2005 Chevy/GMC 6.6L LLY Duramax. Adapters are available in a wide range of materials like Aluminized and stainless-steel to properly match your existing exhaust application. Y-pipes and exhaust reducers typically start at 3.5" and go all the way to 7" in diameter so that they can be used in a wide variety of applications. Get industry leading manufacturers such as Silverline, Magnaflow, and MBRP.