The PPE 117000700 3" Stainless Steel Downpipe for your 20115.5-2016 GM 6.6L Duramax LML allows you to removed your crushed oval stock downpipe and replace it with a smooth round, long lasting 304 stainless steel down pipe. Spiral wrapped with titanium woven thread for superior heat that's held in place with stainless steel clamps.