[cons]

I second this.

Originally Posted by NeilBlanchard

Start with blocking the upper opening, and seal the hood gap with the squishy foam gasket from the home center. Then I'd try blocking the middle opening, as well. If possible, I'd run it with just the lowest opening unblocked. By deflecting as much air as possible up and over the (relatively) smooth body; and prevent as much air as possible from going under the truck; which is much rougher.

Is there a gap between the spoiler and the bottom edge of the radiator? If so, you can block it off which forces all the air coming into the grill to go through the radiator. It may well be open because there is way too much air coming through the three grill openings. You can "tune" things to leat only as much air in through the grill as needed, but then "use" all of that air to cool the radiator.

By having the air intake near or just below the stagnant point is the most efficient, I think.