Well the only thing you can get on a milage chip is only maybe 1-3 miles per gallon more. Yes, in overall that is good, but conditions also apply. I was going to get one for my truck but I didn't have the $400 for the chip.
DRIVING CONDITIONS AND MAINTENANCE MEANS A LOT to get the best performance, AND MPG, and life out of ANY vehicle deisel or gas!
Here is some advice that many may not or do not know, especially if you are pulling a trailer.
You will LOSE about 1 MPG per every 500lbs you are hauling. How do I know? I pull trailers quite a bit and I had researched this years ago and found out why my mileage dropped 5-8 MPG pulling my trailer.
Also keeping your RPM at or just below 2,000 will give you better performance in mileage, YES that would be around 69-72 MPH. Yes, that means you do the speed limit on the highway, IN THE RIGHT LANE. The less speed you are going with cruise control on the better your mileage! YES, NO ONE wants to drive slow including me. But with fuel prices rising, I drive like grandpa now a days!
If you have an overhead console with the MPG average display you can see the changes of performance in different areas of RPMs and driving speed. I ALWAYS use the cruise control on the highway. Your engine maintains speed and engine RPM on level ground and sometimes going uphill depending on the grade of the hill.
There are several ways to get better mileage and performance, (not the hopped up ones), but spending a little money on modifications like direct open air intake stage kits, 4" exhaust system cutting out the catalitic converter, to allow exgaust to move more freely, (BUT, you may not be able to do so depending on your state for emissions testing), Also, keeping your timing, and tune up of fuel and air adjustments in order to get peaked performance, just like as if you had a car doing routine tunes ups, you know spark plaugs, (yes I know deisels don't have them), air filters especially, and changing your oil regularly.
I know I always buy Castrol GTX for deisels and always used it and it is a good motor oil. Even though you can change your oil every 15,000 miles according to the manufacturer of the oil. I change mine every 8,000 miles. Yes, it costs me $87.98 every time I buy the oil and filter doing it myself!
Before you spend the money, I would join a deisel forum, (I have for Ford Powerstroke), there are several for each manufacturer of trucks. There are people on those forums with same trucks that has done everything with them and have experience, also there are MASTER TECHS on these forums that can also give you the correct answer, as well as tips on fixing minor issues to save you money. My FICM, (Fuel Injection Control Module) went out, and after reseaerching because I didn't want to pay the $900+ for a new one, I found in the powerstroke forum a simple repair due to cheap manufacturing. Simple fix myself or anyone, but one has to know what they are doing. Now I have a local shop that I repair their FICM's for a $100 bucks each
But like I said, before you spend your money, (because there is so many different products out there, like metal detectors and it leaves one not sure which one to get and everyone has an opinion), Join a Dodge deisel forum adn you might be able to get better insight as to what chip if any you may want to get. Also word of advice. My friend who owns a deisel shop here in close to where I live has had several people get some performance chips and it later ended up messing up their trucks computer because of wrong programing. Truck just needed to be reprogramed, but that requires bringing it to a shop and can cost you $500+ bills depending on shop.
Most programing chips one can make adjustments to whatever they want. My personally in my opinion, there are too many buttons, decisions, etc, on many of them that you program yourself.
Good luck!
