Originally Posted by Nck
If your looking at these kind of hoods. I would recommend one with a forward facing scoop (one that's functional) a lot of them are non functional, and are just for looks really (utterly pointless) But a functional on my last truck actually forces more air into the engine compartment. keeps it a tad bit cooler inside. But a rear facing scoop helps to because more hot air is able to escape.
I have also heard of people redirecting their air intake to the entrance of the scoop, thus forcing more air into the engine itself. Not a bad idea
By "rear facing" I assume you are talking about a cowl induction hood. They actually do a lot more than just let hot air escape, it actually takes advantage of the higher air pressure built between the rear edge of the cowl and the windshield. Pretty cool effect (no pun intended lol).