All you do is pop your hood and unscrew the cap, flip it, and screw it back on. All this did to my truck was give it a more swirly/sucking sound. Sounds pretty good. Sounds vary on vehicle.

Note: If you flip your cap it sucks in more dirt and get takes all the hot air from your engine..which is what you DONT want. If your going on a long trip I would recommend flipping it back over so your engine doesnt over heat and keep an eye on your filter because you'll need to keep it clean.