I have a 04 ford f-350 crew cab short box with the 5.4l. It has a k and n cold air intake and a flo-pro muffler. Since I had the muffler change from the stock I have noticed that my mileage has gone down from around 15 to 12 and lower. Could it be that I lost some back presure from going from the stock to the flo-pro that only has one baffle in it? What does anyone suggest on a muffler besides stock to get my mileage back up and keep my perforance?

 

is that the 5.4 triton or something else? i doubt changing a muffler would cause you to lose 3+ mpg unless it's plugged up or otherwise defective. have you inspected your cats?

 

It is the 5.4 triton. I haven't checked my cats. would that cause mileage lose?

 

if they're broken or plugged up, absolutely i've never experienced a situation where low back-pressure caused you to lose gas mileage. how's it running? any misfires? vibration, etc?

 

hooker aerochamber. i sound like a broken down record player, but thats the best bang for your buck IMO. look at my youtube vids of my aerochamber

 

I thought they put the v10 triton in the f250 and up trucks?

 

not always. it's an option, but it doesn't come standard and is a shitty design IMO

 

indeed. V10 F250 FTL

 

I think your foot has alot to do with the gas mileage decrease. Truck sounds better now so you lay into it more often!

 

heck it only has 42000 miles on it, havent noticed any weird stuff going on with it...