There is no ram air effect until above 120mph. That'* why I chose vents instead. I know I can blow leaves out of my vents by turning on my high-speed fan override. And in the summer at a stoplight or at the track, at idle I can watch the heatwaves rise out of them.
I recall I measured the heat one time coming from them. I'll see if I can find it.
Keep in mind mine and John'* are functional. And they're the only two cars on this Forum with functional hood mods. All those above that you see are non-functional appearance mods.