Diesel Tuner

If your extended warranty is actually through RAM, be very careful. There are ways to see it has had a programmer on it and they will deny warranty coverage because of it.
Dont get me wrong, I'm a proponent of a good programmer (it really wakes it up) but at the same time I had to decide to be your my warranty coverage.
If you still want to proceed check out Smarty. They dont exceed any of your systems parameters like some do and there's nothing to put on the truck beyond the program.

Newer vehicles are seeing less and less positive results out of tuners. EPA regs a few,years ago effectively cut the legs off the tuner industry. What we could get 5 years ago allowed a person to lay down a lot of power. Now? Not so much. For a tuner to really work requires a lot more than simply adding a chip, box or whatever you want to call it. Just not really worth the 6-800 dollars for the programer.

Take Bully Dog 50 state legal off your list. I bought one and had it installed and when I entered vin for my 2010 Ram 3500 last year and they did not have a tune for pickups only cab and chassis when I called the help line. They told me to check back in several months and so far no tune yet since Feb 2015. Tuner listed 2007.5 thru 2010 Ram 2500/3500 CTD on the description when I ordered it on line. Maybe they have one for a DEF Ram but I would doubt it.

If you want to retain your warranty do not put a programmer on it.

Calibrated Power Solutions. I use their emissions intact tuning on my 2012. Its amazing. The transmission tuning that goes with it is unreal. Exhaust brake works down low where I need it. 15 mph down hill entering or exiting a campground where the speeds are low is effortless now with no input from the brake pedal. So far fuel mileage is about 1 mpg more so theres no real benefit there but the power is nice.

I'd wait until the warranty is up before you modify the truck. Honesty, if you want better mileage, slow down a bit and ensure your tires are inflated to the correct presure.

Use Tow/Haul Mode..........

I have an older Dodge Ram with the Smarty Programmer. The Programmer is really good. Using the lower programs can really wake up a Dodge Diesel. However, when you change the computer tune you are your own warranty station.

In socal they will scan your computer, and they can tell if you had a programmer installed. Our truck is kept stock, works fine for our towing needs, even if I don't get an extra 3 mpg and magical shifts out of the tranny.

And I saved money.

I would do some reading on a Cummins forum before tuning. I think the 68rfe is not really up to the task.