i agree with the other guys its out of warranty so just delete it and be done.
but there lays a problem as well, if you want to go the H&S route it will cost you 2k just for the tuner that can do off road tuning cause the new street tuners do not do off road tuning.
i dont know if spartan is still offering off road tuning or not, so its a catch 22 now, do you replace the dpf cause it sounds like its plugged up and will get worse. ( i suggest parking the truck till its fixed ) or do you just bight the high price aftermarket stuff now and delete it and move on.
coming from a guy who deleted his truck at 10k, ive never been happier with my truck, after the deletes it runs better, clearner and gets better mpgs that it ever did bone stock.
i can average 16 city mpgs and 18-20 on the hight way with the set up in my sig.