The early 6.7's will need the turbo cleaned every once in a while unless you delete them. Don't ask in the forum how to delete, some of the mods get a little pissy when that gets discussed vs other "illegal" things that are discussed frequently.
The VGT turbo's get gummy unless you are working the truck most of the time. When I was pulling trailers all the time, mine never had an issue. Started using it as a grocery getter, and it got clogged up and needed cleaned several times (thankfully under warranty).
Since the emissions stuff rusted off, I haven't had a problem, get 22-26MPG (sometimes 18, if I decide to use all the extra ponies all the time), oil stays cleaner longer, etc...
EGR delete's are easy on the early 6.7's. I just made my own plates and bolted them on. I also have an aftermarket intake horn, so that side went away anyway, but an EGR delete could be $10 in steel and an hour or two of effort.