I've got a 2001 Ford F-150 Lariat stepside with a 5.4L, 2WD and 65k -- What is the best type of air filter and muffler to get the most mpg out of it?
I've already changed the spark plugs -- fuel filter -- fuel injector cleaning -- flushed the radiator -- changed the oil using Vavoline and a Lucas addititve -- I've got power -- power I'm not worried about -- I need mpg -- mechanic told me that K&N, and a Flowmaster would bump my mpg up, is that right? I've got other things wrong with it, but I'll worry about those later. ;-)

 

Flow Masters with a crossover will help it breath, KN wouldnt hurt. Better it breathes the more power and efficient it will be;also check tire press and alignment.