WXman

Interestingly, I had just posted this yesterday:

https://www.f150forum.com/f11/anybod...xhaust-329237/

I'm thinking about putting the factory resonator back on to try and get back some of that old feel.

SnowDawg

I actually got much better mileage out of my 5.7 Hemi than I do my 5.0L.

Mike@Flowmaster

Flowmaster's chambered muffler designs scavenge exhaust gases, which increases exhaust velocity and allows your vehicle to run more efficiently. This frees up available power and can give you an increase of 1-2mpg depending on how you drive the vehicle. However, it is important to use the correct Flowmaster muffler for your application.

This doesn't quite look like one of our Cat-back systems. Haulinbass09, would you be able to check the inlet side of the muffler case for a part number? That way I could tell you what kind of Flowmaster muffler they used when building that exhaust system.

BurntToast

I have put exhaust on all my vehicles and I can never tell a difference in mileage or power. Maybe it is just me. I always just did it for the sound.

MurderFX

Like others have said, Any loss of mpg will be due more to driving habits, than exhaust system.