The Banks diesel tuner kit would be about the LAST thing I'd put on my new diesel pickup. Too many better tuners for diesels out there, and cheaper too.
SON bought a new '14 Ram 2500 CTD off the lot about 3-1/2 years ago, stock tune was 370 hp, could get 22-24 mpg highway on trips, no idling. Had a "Contaminated DEF" error code, dealer reset computer while he waited, when on his way, second time, dealer needed to keep his truck, single car with two people working different shifts caused problems but they worked around the problem, third time dealer said it would be week before they could look at truck, service writer, Scum of the Earth IMHO, kept asking if Son was using Mopar DEF, No, same stuff Hundreds of trucks every day buy from the Flying J truckstop. Truck was Deleted, didn't use DEF anymore, tune was 500 HP, big shiney exhaust. MPG dropped on his truck too. He never pulled 6000# trailers, more like 16,000# to 20,000# pound trailers.
Then there's me, my 1996 F-250 7.3L PSD is still pure stock, 210-215 hp, I did run a K&N drop in air filter in it for about 50,000 miles, till I cleaned it and saw Thousands of points of light thru it even with the new K&N oil on it, put a new OEM filter in it, will never use a K&N again. My oil analysis with the K&N showed 3-4 PPM silicon, DIRT!, with OEM was 0-1 PPM. Truck has 300,000+ miles, towed up to 20,000# gross, about a 13,000# trailer. All with stock tune.