Gain up to 10 additional RWHP with our cast aluminum high flow intake horn for the 2017-2019 L5P 6.6L Duramax! Our intake horn directly replaces the smaller (2.4"" diameter) plastic molded stock intake runner with our larger (3.3"" diameter) cast aluminum model. Kit Contents: Cast aluminum intake horn Square cut O-ring Billet aluminum fitting for PCV connection M8x1.25 mounting hardware Application Notes: This intake horn is a direct replacement for the stock GM intake horn. No modifications or tuning are required to take advantage of this simple upgrade!