my dad recently purchased a 2005 3500 2wd 6spd dually with 3.55gears to pull his 30 ft camper with. i told him that we could maybe get him close to 20 mpg while he was towing. so what ive done so far is intake (s&b), exhaust w/muffler, and guages. my question is what else could i do to help him out. i know a programmer and/or chip, but i do not know which one to choose. and after that what else could we do.

 

I would look into a custom shell for your Father's truck aerodynamics is key. Next I would do is look at driving habits, low rolling resistance tires, a programer might help. intake and exhaust would be good to get the benefits of the programer. Thats the farthest I would go with the power-plant. no need for injectors, or anything else. many of the people going for fuel ecconomy dont really see any gains from stage 1 injectors.But aerodynamics would be for you. lowering the truck would help?
Two sites to look into:
You can then track your progress with this site:

 

wow....20 mpg while towing? good luck with that. I get 22 running empty-sometimes up to 24. mileage drops to 16 when towing a 12k 5th wheel. mine is a 6 speed h/o with the edge e z, 4" exhaust, and cold air intake.
If you keep the rpm's in an acceptable range(2k or below for a 24 valve, 2150 for the cr) that's when the mileage will be at it's best.
keep in mind that these engines werent built for good mileage- they are built to work. quickest way to ruin a cummins is to "lope" it around. my advice would be to keep the mods simple, let it breathe, and work it hard occasionally. stay away from edge tuners- they raise rail pressures a bit too much. their tech support leaves much to be desired, and when mine gave me problems, their fix was for me to buy a new one. Smarty gets good reviews, I'd check them. in short, intake, exhaust and a mild tune will likely yield the best results while maintaining dependability.

 

2wd 6speed add a programmer papaw it and i could see possible getting 20

 

if all it is is highway 20mpg towing is possible. Your truck and load needs some way of directing air better.

 

get a smarty good for about 3-5 MPG and lots of power! Sea bee's "CAN DO"

 

hoorah seabees! yea i suggested to him the 19.5 wheels for the more mileage highway friendly tires. the fitted cap is no deal since its a fifth wheel camper.as far as his driving habits im sure it will be the 100% opposite of me so very mileage friendly, and it 98% highway driving. im pretty much sold on the smarty but which one?? and anyother ideas? we are open to all possibilities.

 

[I] have a 5.9 and I pull a 33 ft fifth wheel at about 12,000 lbs and I get around 10 mpg I don't have a tuner, I do have a k&n cold air intake and a MBRP 5in exhaust, i am thinking that I may look into a smarty if it improves the mpg that much.

 

Smarty Jr. if hes going to be towing and isnt looking to boil the tires and kill corvettes