Awesome A-body air dam for under $30!

Did you guys notice any cooling effect w/ the air dams ? Been thinking about one on my 68 fastback, but it`s already low enough that I cant hook up anything to tow it with, w/o bending the front splash pan(valance). "Hoping I won`t need to !''
The Camaro dam made a tremendous difference once moving. It apparently forces large amounts of air into the radiator. The Ford dam is much more vertical, so it might not make as much of a difference?