I used an 11x5 K&N velocity stack base style assembly inside the hood scoop with an isolator plate. Didn't hurt it. I think it helped it. I don't think I would run one without an air cleaner anymore and K&N makes a lot of different sizes, shapes, panel filters, etc, that you can get a filter on just about anything. If a 14 or 16 x 3 or 4 round unit will work, you have more choices.