I recently did a lot of upgrades that I thought would improve my gas milage but I guess it hurt it. Example; K&N Airfilter, Flowmaster Catback Exhaust. I've calculated two tanks of gas now and I'm getting about 13 mpg. Does that seem right???

 

What were you getting before?

And you are never guaranteed to get an increase in MPG.

 

It depends on your driving. My commute is 23 miles each way, with about 1/3 city streets and 2/3 freeway, (sometimes stop and go). I get 15.5 mpg with the 4.6 v-8, k&n intake system and gibson 3" exhaust. If your driving is all city streets, your mileage will be worse. All freeway driving at approx 70 to 75 mph gets me 16 to 17 mpg.

 

I commute 35 miles one way to work. Mostly highway about 90%. I used to get about 15 miles to the gallon the last time I checked. Well the only thing I can think of is I like to sound of the flowmaster exhaust and maybe I'm getting on the peddle a little to much to hear the awsome ford power growling from behind me.

 

Dont feel bad. My 97 5.4L only gets about 13 MPG on the highway, and thats when I have a tail wind. I always shake my head when I hear of people getting over 15 MPG with the 5.4L. I heard some post MPG in the 18-20 mile area.