Nahh....
Al is pretty much right on the ram-air thing...You are already rammin no less than 12psi anyway...LOL..YOu aint gonna get that from a ram-air hood at Mach speed..."Grin"
The cooling thing is kind of a "Contrair" to what Al is proposing though, since many SC'rs have experienced overtemp problems after getting more air traveling through their engine cavity...Just from what I have read I would say do as much as you can not to upset the air passage to and from the cavity...
Also you may wanna search through some old subjects related to your questions, and you will see where I am coming from...
Cheers