S&B Cold Air Intake [75-5140]

A sealed airbox and a larger filter that replace the factory intake so the turbo draws more air and less hot underhood air. S&B measures 39.05 percent more airflow and 99.42 percent filtration efficiency on the cotton cleanable version of the filter.

why this one — S&B names F-450 and F-550 in the fitment, so it physically fits the dually rather than being an F-250 kit you hope clears. Read the emissions line carefully before you order though, because it is the reason this row exists as a warning as much as a recommendation: the CARB exemption D-590-57 covers F-250 and F-350 only, and S&B states plainly that there is no CARB EO for F-450 and F-550. If your truck gets tested where you live, that is a real problem and not a footnote. This is not legal advice, just what S&B publishes.