6.0 gas mileage? does this sound normal?
 

so i have had my 6.0 for about 2 months. when i bought it, it already had a bullydog PMT in it which is great for gauges but the tuning on it kinda sucks IMO. but anyways i had never even checked my MPG until this morning because my truck seems like it sucks alot of fuel, and it said 13.5.....is this normal? i do normal driving, no dogging it out or anything and most of the time im driving 55 mph for long periods of time. the truck is leveled with 35s, CCSB, 4x4, Bullydog, 4" straight pipe, and a k&n cold air intake. just wondering is there anything i can do to improve this?

First off, I wouldn't trust that module, I always hands calculate mine and always fill until I see fuel in the filler neck. That is the only way for consistency, once the pump clicks there is still room for 3-4 more gallons. Another thing to make sure of its that your odometer is correct, because of my tires mine is of by 10%, so when my speedometer says I'm doing 65 mph I'm actually doing 72 mph as per my GPS and a buddy with a radar gun. I used to be in the ballpark of 15-16 mpg until I learned how to calculate it and understand the difference in distance. When the truck would say I went 540 miles over 33 gallons (16mpg), I was actually running 600 miles over 33 gallons (18mpg). Your best mileage is going to come from 60 mph from what I've noticed, 55 is fine but much lower than that and the engine isn't in its sweet spot and over 70 is the point where the wind resistance is too high for the truck to efficiently maintain speed.

Im running 33's with a leveling kit, SCT and EGR Delete, stock exhaust and I am getting 12.8 mpg. This week I am putting on a 4" straight to 7" miter and I'm hoping it goes up one or two.

Guys that are getting 17+ must be running stock tire sizes or one heck of a tune, cause I can't figure out how else they'd be doing it.

ive just completed doing an egr delete, sct tune, coolant filter , up graded to a 58 volt ficm..........and im getting 17.4 to 18 mpg

stock tires on a F350 2005 / 6.0 with 185,565 miles ....tires are stock 275-70-R18

will be doing the blue spring up grade in a short bit too

i am getting 16 mpg
coolant filter
58 volt ficm
oil by pass kit
SB filter

Mine is leveled with 305/70r16 and a k&n air filter I get around 13 on the module but when I keep up with the miles and gallons used its around 14.5-15. I'm about to add a 4" exhaust and see what that does

13 is about all you're going to see, unless all your injectors & your HPOP are in pristine condition.