there will be some cutting involved in the front wall of ur rad, ive sceen this done to many NA's with improvements in responce not proven if any HP gains

 

That picture is of high and low pressure on the car, not a flow profile, but a pressure profile. Think about it, almost all cars produce lift. Invards means high pressure, outwards means low pressure, and the overall trend is for low pressure along the top of the car, making lift. It won't be perfect for every body style, or for any point on the car, it's probably along the center line. There is still flow everywhere though, but as with anything there's a boundary layer of slower moving air right along the surface. That's why a scoop works better than a duct, especially in low pressure regions.