Ram air intakes are a poor man's forced induction system. It uses the speed of the vehicle to force air into a scoop that is attached to your intake, resulting in easier breathing for your car. If your engine is working to induct air, would it not make sense that if you gave the air (instead of it taking it through vacuum) it would result in more air getting into the engine, resulting in a power gain.
Of course, this opens up the discussion of where the true bottle-neck resides... how is your air filter? is it restricting flow? do you have any tight areas in your intake tube? and more...
I had a nifty setup on my 1983 RX-7... the carborator snout shot towards the radiator shroud area, obviously pulling significantly warmer air than if it were in the fender wall. So, I cut a hole in the side of the shroud, put an exhaust flex pipe through the hole and into the snout. End result was that at highway speeds, I was effectively taking in the coolest air I could, given the situation. The only thing better than this setup was the headlight-scoop option that Mariah Motorsports used to make...
Ram air is a good thing. You just need to make sure you're not hurting the aerodynamics of the car, and are not un-intentionally creating a bottleneck that was not present previous to the modifcation.