Got a white lariat fx4. Hard tonneau. Was getting 23.4-23.4 average. Put on K&N CAI now I’m getting 23.7-23.8 mpg. My commute is part high mostly town driving 32 miles round trip. I use regular 87 oct gas. Full tank gets me low 400 range. Dual exhaust on its way. Will let you know if it helps.