I have an '05 F250 w/ the 5.4L. Currently I am running K&N FIPK and Gibson Dual-Sport exhaust. I've found modest gains in MPG (0.5-1.5mpg gains) and little to no gain in the power department.

Would running a Tuner with custom tunes for solely MPG gain and one for sole power for towing actually make that much of a difference for my application. I drive 5 days a week close to 100miles a day...and pull anywhere from 5000-8000lbs on weekends.

Can anyone give me numbers or examples?

Thanks guys...

 

I can't do you any good on the 5.4, but I can tell you about custom tuning in general. Where the custom tuning really shines is when you have an auto in particular. For towing, people are able to have the truck shift when it best suits your driving style is the best thing for economy(in my opinion). If your truck has shifting patterns that are at odds with how you like to drive then you might see some lost economy there. As far as economy goes, more often then not people see better economy with a street tune then they do with an economy tune, because you don't have to be on the throttle as much, but you have to drive that street tune with the mind toward economy otherwise it won't work like it should(and that's hard to do, trust me). Overall, custom tuning just allows for more options on the owner end versus off the shelf tuners. Just a whole lotta my .02 worth. Hope it was helpful.

 

tex25025 has hit the nail on the head with his post. I would add, that with a gas 5.4 a 91/93 octane type of tune with a good torque converter locking strategy will give you better economy...As far as numbers you will get a lot of different answers. A good rule of thumb is 1-2 mpg increase in gas depending on an owners driving style. A good flash tuning device not only will help in increasing economy of your truck but overall drivability will be improved also.