Dart 340 twin hood scoops

There is very little RAM air effect below 100mph. The intake air into the carb is traveling too fast and to have any kind of RAM effect it must exceed this. This is obvious in aircraft where thy only put a scoop on turbines if they are capable of speeds higher than this. Check out crop dusters with no scoops. There are a ton of factors that go into when and how a air scoop will be able to provide any effect at higher speeds. Most street cars will never see a speed or have scoop design that will matter.
What scoops do provide is cool air, and this can make a big, big difference, but it won't likely be apparent on a Dyno.
They do look cool, especially from the drivers view. I had them on my Demon years ago. But since they never came stock on a 340 Duster ( they did come on Twisters, but there was no 340 Twister) I have resisted the urge to install them.

Here is some good information on air scoops, which if really designed carefully can reduce the vacuum in an air scoop and have a CASS of 50 mph or so.
Air Scoop data