How much does a hood scoop actually help?

I'm not sure if this is better suited to one of the engine forums or not but I figure that it might fit here too.

I'm excited to get a fiberglass hood for my Dart to shave off another pretty good chunk of weight. So far, I like the looks of the lower profile "six pack" style hood offered by AAR Fiberglass... but I'm weighing my options on a few points before I take the plunge.

Obviously cool air is a huge help for an engine...but assuming that the car is moving and air is rushing into the engine bay, how much benefit is there to having a scoop? Is it something that you would actually notice? Would it show up on a timeslip?

If there are benefits, do you need to seal the air cleaner to the scoop to achieve these benefits?

Currently, I'm just not sure if I want to make my car look that aggressive. For the moment, I have a pretty mild small block (~300hp). I'd like to go for a stroker kit...some day but for now my car isn't exactly a rocket ship and big scoop seems almost "ricey." If the advantage offered by the scoop is small enough, I might just go for the flat hood and fly under the radar.

Of course, if it made a really significant difference or if it would be more important down the road (with bigger hp numbers) I'd be fine with it... :)

Thoughts/opinions are very welcome.