Outside of the costs to buy, and modify a new truck, there is also the cost of a catastrophic breakdown, that will not be covered by warranty, due to mods, and removal of emissions equipment. I like the relative simplicity of my old dinosaur, and even if I have to spend more money, to make x power...I am starting off with a paid for truck, that I gave $3500.00 for. I have my Denali, or my 2015 tahoe if I want amenities, or luxury crap. For truck stuff, I don't need cooler or heated seats, navigation, sunroof etc. The power to match what new trucks have is easy and relatively cheap to come by...it's the niceties you pay for. Don't drive it like a retarded 16 year old, and your fuel mileage will come also. You will have to be really nice to a 6.4 to get 20mpg too..it won't come automatically with deleting and tuning it. I run 34" tall michelins on factory 20" wheels, and at 70mph turn 1700 rpm..I have got as high as 19mpg mixed driving, hand calculated, bone stock. If I got the truck to 340 rw, and mileage dropped to say...15 mixed..that's as good of mileage as a deleted and tuned 6.4 in town, if not a little better...the same rw roughly as a 6.7, and more power than a stock 6.4, and into 6.7 territory stock. No expense of the big stuff that can break, and still comes in over $30k cheaper. Do you realize that your "buy a new truck, because it gets better mpg" argument is void?? That $30k I save in my old truck will buy a lot of damn diesel..more than I would probably run through it in my lifetime at this rate. Yes, it's nice to say you have something new, and all of that. But when something big happens, and you are left holding the bill...