A "cold air intake" is not going to affect your gas mileage. In fact, most of them draw warm, engine-compartment air. They're really just noisemakers on these cars. Your original intake does a pretty good job of drawing cool air from outside the engine compartment.
If you can find or adapt a long ram intake like a Legmaker for your application, you might see a drop in intake air temperature, at the expense of a tricky install and making your future air filter changes a pain in the ass.
