Hello everybody,
I am new here, and this will be my first post, but I plan on being a long time user of this forum as I have already found lots of useful information while googling questions and issues I have had, and almost all of my searches have brought me here! So currently I have a 2004 F250 Crew Cab Lariat with the 5.4, with 141k miles, and I have a 1999 F250 Super Cab with the 6.8 that I plan on keeping and using as my daily. Right now it has a small lift (maybe 3”?) and is running 35s on it, and it has a dual exhaust. I’m not super knowledgeable about vehicles, but I work around them myself, and always google how to do something and then fix it myself. I have recently replaced the water pump, vss, and cleaned out the rear differential in the 99. I’m looking for fairly cheap upgrades to make the truck sound better, and get better gas mileage. More power is also always nice, but I don’t tow anything too heavy, so it isn’t necessary. Are there any upgrades or work any of you think is worth doing to it given the age and mileage? I plan on babying it, and majoring everything the best I can to make it last as long as possible. I was maybe thinking a cold air intake, possible a better aftermarket exhaust, and maybe changing the gears? I haven’t looked to much into the gears but I keep seeing that on all the forums saying it is one of the best investments I can make, next to a custom tuner. I was thinking of finding a used tuner, I just can’t see myself spending $500+ on a new one given the year and mileage. Would it be worth doing that to this vehicle? I also do have other vehicles I can be driving if it takes me a while to do something to this truck. Thanks in advance!

Edit: What gears would be best for gas mileage for highway speeds of ~75mph without towing anything with the 35s on, or just having my atv and dirt bike in the bed, as this will probably be how I most commonly drive the truck. Thanks again!

A cold air intake will add nothing, in terms of HP and gas mileage. Most of them do a good job of bringing in the heated air from under the hood.

Most, if not all, people that change the rear end gear ratio do so because they want more bottom end “pull” for towing, and it also makes the truck feel like it has more torque. The trade-off is a loss of MPG. Unless you are moving up in gear ratio, from 4:10 to 3:73, for example. Gears aren’t expensive but competent installation is.

Yiu can easily change the sound by swapping out the muffler for a performance unit. Just keep in mind that some will produce, at certain cruising RPMs, a drone that you might find irritation.

Just my 2 cents.

— Dave

For mpg at 75 I would suggest leaving the 3.73’s in it if you want more umph off the line and better performance towing and around town then I would move to a 4.30 with stock size tires for your 35’s 4.56 or maybe even 4.88 would be an option especially if you were doing a lot of towing with the 99 non pi v10 that’s a bit down on power compared to the later pi motors. As far as exhaust the only muffler I’ve ever heard on a v10 that sounded decent is the aero turbine 3030xl and Jones also makes the same one the xl means it has a resonator in the muffler that tones it down some more the regular 3030 is too much on a v10 I think as they aren’t a good sounding motor. There is a video of a members v10 with that muffler I’ll link later for you.

You Tube