There may be some validity to Jacks' point regarding air/fuel ratio impact at high speed, but not an issue if you are running EFI.
Carburetor's respond to changes in air density too.
I often chime-in on the topics of ram air and cold air because the two are often confused. They are not the same subject. The horsepower produced by any engine operating at any speed benefits from lowering the temperature of the air it inhales. There is a 1% horsepower improvement for every 10 degrees F the air temperature is lowered. I learned that when I was about 10 years old. It is TRUE that ram air is only effective at illegal speeds. If you're not racing, there will be no benefit from "RAM AIR" but that doesn't negate the benefit of the cold air that the scoops shall pull-in.
Cold air is a viable goal, but there are certain BIGGER issues I think should be prioritized and emended first before putting time and money into cold air:
(1) the emissions tuned factory carburetor should be replaced with a carburetor tuned for performance,
(2) the engine's compression ratio should be raised to approximately 10:1.
(3) the exhaust system's performance should be improved
(4) the exhaust heat should be blocked from the intake manifold.
Finally … to recover the good mid-range power that comes from heated air causing the fuel droplets to flash into the gas-state, you need to utilize a carburetor with annular booster venturis, because annular boosters atomize the fuel better, and smaller fuel droplets will flash into the gaseous state more easily than larger fuel droplets.