I purchased a 2014 Ram 2500 with 6.4 about a month ago. The truck is my daily driver and replaced a 98 Ram 2500 with V10 as my TV. Thus far the power and ride quality has been amazing and significantly better than the old 2500 but probably not quite as good as 1500s I have drove in the past. Gas mileage has also been very impressive. Just rolled a thousand miles on a couple hour drive of mixed driving yesterday and averaged 17.5MPG. While the MDS doesn't sound great it sure seems to work well.
I have not yet towed the TT but likely will in a couple of weeks so I will keep you posted. I have no concerns given that this truck has way more power than even the V10 I was pulling with.
