Frank- No testing of the airbox yet. You understand that I am not talking about a TL type "take the top off the airbox" type mod, right? It can't hurt, it was easier to do it this way, and I didn't have to split the box. I was able to do it all through the hole in the top. If you look at the inside of the airbox, the ram air ducting is pointed directly across the floor to the "ramp" looking part just ahead of the stacks below the filter foam. When the air hits that ski jump, it goes straight up and runs into the nasty recessed part of the airbox roof that is inset to allow mounting the filter lid. That part of the box shrouds the stacks, especially the long ones. The bottom of the gas tank is flat. As long as you seal it well, you should be fine. I can't see any way that it wouldn't reduce the pressure drop across the airbox.