On my ITC Crx I do need brake ducts when running at Blackhawk Farms Raceway. I use an inlet duct (not NACA) that is vertically mounted just below the bumper cover and in line with the bolt on lip below the bumper cover. The duct is then lined up so the hose runs along the inner metal fender liner and tucks behind the strut and the opening of the hose is directed as close as possible to the center of the rotor.

This setup works pretty well but I need to watch how much steering lock I use in the paddock area to keep from crushing the ducts.