Dustin, thanks for your input - I have a sheet metal shroud at the bottom of my radiator which extends down to the lower cowl surface. It follows the entire contour width of the lower cowl. However, there is a 1/4" gap between the lower edge of this shroud and the upper surface of the lower cowl, along the entire contour. I'm planning to install a rubber weather strip into this gap to seal it up. That should force a little more air through the radiator and oil cooler.