As usual, I'm probably missing something here...

http://www.lazy8.net/intakesystem.htm

I thought the whole object of the exercise was to take air in through the cowl opening into a diffuser(thoughtfully designed and insulated) of some sort, slowing it down and thereby raising the pressure entering the throttle body...

and that if you do filter the air, this would be done within the diffuser...

and that the diffuser should be built into the bottom cowl...

Angier