Not sure which 2004 Ford Focus Air Filters - Custom Fit is right for you? We have over 14143 customer reviews, with an average rating of 4.5, to help you find exactly what you're looking for. Here's what some of our customers have said:
"I put the filter in with some sealing grease; it fit in nicely. It's only been 40 miles; so far I may be getting a tad bit better mileage, maybe 2 or 3%. The Touareg is heavy and slow with a V6, so I don't know if hp increase will be too evident." —Peter H from Santa Maria, CA bought a K&N Air Filters for a 2004 Ford Focus.