Originally Posted by nikolasv
What is the use of the air box around the air filter?
Can't I just have the air filter hanging there without that box? Does it have to be in an air box?
Wouldn't the air flow to the engine be better without it?
Haha !!!!!! The common mistake !
The air box makes sure that you "suck"

cold air from outside the engine bay ! Usually there is a flexible hose as well attached to your airbox and a plastic vent next to your radiator.
If you leave the air filter hanging there, the only thing you will get is boiling hot air, which is the worst thing you can do that affects the performance of the car ! Things get worse while driving at high speed ! The outside air is pushed inside the radiator to cool it and ends up in your engine bay.
What you need is a Cold Air Intake !
Racing air filter with an airbox is the way to go
Try BMC air filters