Your engine bay is essentially an oven during the summer season. If you have a cold air style intake then yes your engine can breathe better when compared to youer factory air box, however, it is inhaling hot engine bay temperatures. A proper air box can protect your cold air style, or exposed filter from hot engine bay temperatures, and it will allow the intake to inhale near ambient temperatures. This will maximize the function of your intake, and furthermore, it could protect the intake from harmful elements that can become loose in the engine bay or road debris that can become lodged in the engine bay as well. If you purchased a COBB SF Intake for your WRX and want to upgrade to the SF Intake Box then you can do so. There are also many other fine examples from the likes of Mishimoto, ETS, as well as SPT. And if you're currently thinking about upgrading your factory intake, make sure you check out our good selection of Cold Air Intakes, and for those with existing intakes make sure you properly maintain them with the Filter Cleaning Kits and Accessories.