Straight Pipe Monster Muffler Delete kit for 4 inch Banks Power Monster Exhaust Systems. Does not replace OEM muffler Replaces Muffler 53801 used in 2001 - 2007 6.6L Duramax and 1998 - 2007 5.9L Cummins 4 Inch Monster Exhausts. Includes 4 - inch x 36 - inch Exhaust Straight Pipe and all necessary hardware. Banks Power Straight Pipe Kits are made from durable galvanized T - 409 Stainless Steel. These kits come with the necessary hardware for the applications listed in their description.