pics of the airbox I\'m building. Obviously not finished yet. It needs an air intake which I'm working on and to be painted. It's all aluminum. Tacked with a wire feed and then tigged together. It is designed to hold a 14x4" filter but would hold smaller diameters ones as long as they are 4" tall. You could also use smaller height ones if you put one of those K&N breathable tops inside.