Here are articles on study results of air filters you may want to read and then make a decision.

 

If the cai improves your mileage by 1 mpg it'll pay for itself pretty quickly, especially if you do a lot of driving. I'd just go w/ a for sure think like k&n so u know it's gonna work and its gonna last. There's other good name brands too but i'd trust that better than fabbin up my own. It's more money initially but at least u know that it'll pay itself off quickly and after that it's just money saved that u wouldn't have had before. That'd be enough proof for me if i was a dad in that situation