We have a few different choices here for adding some venting to the area of the body between the tail lights of your 818.  If you have your single 3″ exhaust centered in this area, there are a couple different choices for you.  The unit shown with the oval hole pattern could also be made without the exhaust opening….just solid oval hole pattern in that area.  These are designed to fit on the inside of the body, with the perimeter bonded to the inner surface of the body in that area….but as you can see from the photos, it also looks great mounted on the outside of the body.  That particular model was designed for a customer where his exhaust was not centered in that area of the body.  Louvered models will come with braces to hold the louver blades at a set angle.  These will be shipped flat so they can be used as a template to mark the cut openings in the body, and the louvered models will require you to bend the louvers to the proper angle by hand and install the braces onto the louver blades.  Made from .080″ Aluminum.