Hello from Virginia....Purchased a new 2018 Big Horn with the EcoDiesel. I found this site during my search for ECM tuners. I would love to hear and feedback from users of the GDE Hot tuners for the Ram ED's.
Glad you bought it new and glad you are considering the GDE hot tune. I stumbled onto GDE after a guy told me I made a huge mistake buying my truck in 2015 due to engines grenading. 80% of my driving is highway and 20% is stop and go. The truck says I average 26.5 mpg. I average 78 mph on the highway using cruise control. My wife gets 32 when she takes it on a trip. At 75k miles, my truck has never had a warranty repair. People without this tune are having problems with fuel economy and engine sooting.
I would recommend a 5000 mile oil change frequency if you don't tune your engine. I think the main bearing problems with this truck is caused by soot in the oil reducing the lubricity of the oil. The EGR system is the devil to this truck, just like it was with the Ford 6.0.