I have seen a few cold air intake options online as well. I have to ask you, if you are trying to put one on for looks, or better performance. I ask because the Elantra already has a cold air intake, since it pulls its air directly at the grill. The idea of a cold air intake is to allow colder air that is almost forced into the intake. Not trying to bash on aftermarket parts, but I had found an interesting video where they were testing aftermarket intakes on the Elantra, and they found that the factory intake out-performed the aftermarket ones...but only because of where the Elantra is pulling air.
You are 100 percent correct. Stock cold-air boxes are generally superior to the aftermarket, especially on a stock Elantra motor. Just make sure the filter element is kept clean and when ready, replaced with a quality, not cheap, replacement. My wife's Ecoboost Mustang air box is superior to any aftermarket. It just doesn't look sporty enough for some.