I know it's an old thread, but maybe it will be a timely resurrection for someone
As others have said the 6.0 can have its problems that have been talked about over and over As for fuel mileage and tuners YES you can help with a tuner and the right tune... I have tried 3 different tuners Hypertech, Edge and now a SCT, hands down I like the SCT with a tow tunes from ******** automotive performance. The Hypertech had the best fuel mileage but they do not have a EGR ****** tune and I would turn on the check engine light from time to time and put the truck in limp mode and had to pull over cycle the key and go on...what a pain in the butt As for the Edge I did not like the trans program.
So all that being said with the SCT tuner and ********s
https://mechanicguides.com/best-diesel-tuner-for-6-7-cummins/ studded tow tune I picked up 2.4 MPG when towing and when not towing I run ********s Extreme SRL tune Also keep in mind I'm a overkill type when it comes to mods so your mileage may not be the same..
My list of Mods:
* ARP Head Studs
* Maxxforce Oil Cooler
* Blue Spring Fuel PSI Reg
* Updated HPOP Fitting
* High Flow Turbo Oil Supply and Drain Fittings
* Sinister EGR ******
* AFE Intake and Air Filter
* Bullet Proof Diesel Water Pump
* Mishimoto Radiator
* Evans Coolant
* Mishimoto Intercooler
* Mishimoto Intercooler Piping
* MBRP 5in Exhaust
* 5in Aero Turbine Muffler
* Mag Hytec Front and Rear Diff Covers
* Mag Hytec Trans Pan
* 6.4 Banjo Bolts
* Boost, Exhaust Temp, Fuel PSI and Coolant PSI Gauges
* Coolant Filter
* RDS 60 Gal Transfer Fuel Tank
* Ride Rite Rear Air Bags
* B&W Companion 5th Wheel Hitch
* SCT Tuner with ******** Custom Tunes