I see people recommending CIAs and K&N filters religiously, especially on this forum. These guys are great and vary honest about the performance difference. The biggest difference is in maintenance not performance.

These guys are funny and put it on the dyno to prove their conclusion.
Now this doesn't mean the factory intakes are perfect, it just depends on the manufacturer.

It really comes down to preference, I prefer the paper because it does just as good and over the time I own the truck its still cheaper to replace a 14x3 paper filter than to buy a k&n plus the oils and cleaners for it or to replace the stock paper filter. So I prefer the cheaper option.

 

I have a k&n filter in my stock air box, I found it at a pic n pull and paid two dollars for it ( Great score for me ). I live in a farming area, so there is always a lot of dust in the air, so the oiled filter works better for me.