Have had many people wonder about how a flame arrestor can be so restrictive, and how these throttle body mods actually work.
Air is a weird thing, you cant see it moving, but it acts a lot like its cousin, WATER.

Try this experiment sometime.

Find the slowest, laziest flowing stream, creek or river you can. Add certain obstacles in the slow moving current. A small stick, a rock, even some chicken wire, which would simulate a flame arrestor. Watch what the water does when it hits these obstacles, and after it passes by them. Those swirls created when the water passes by the obstacles are called turbulence.

Now take a funnel, lay it in the flowing stream of water. Watch how slowly the water enters the funnel, and how quickly it exits the funnel. The speed of the water is accellerated as the funnel narrows.

Having trouble seeing this in the water also? OK, cool. Now add the food coloring of your choice in the water in front of the obstacles and sit back and watch... Bet you find yourself saying, wow man, check that out!! I didnt think it would do that!

Just an interesting experiment you can do that helps your mind actually see what is happening with airflow and engines....