Just a little info that I have found over thee years of running GNCC race teams. We run races for two hours in all kinds of conditions. No matter what air cleaner we run the outerwears are a must. The trick to them is they act like a magnet because they have static and it traps the hard metals that do the most damage to the motors. The sand dunners should all ready know this but if not there is some info for you.

I have not looked at what to build as far as a air box yet but when I am dynoing our v-twin quads the fan blowing on the front of the quad pushes alot of heat off the motor up in to my face.The fumes or dirty air and heat can cause a lose in HP so I want to make sure any air being taken in is cool and clean for the best performance. I have even thought about building a box with dry ice in it for my short track racer during those 100* plus days.Just something to think about.