Ok so I want to do the egr and dpf delete but I can't decide what size exhaust to get. The trucks stock but I've been looking at 4in or 5in mbrp exhaust,most likely straight piped. I need some help choosing, does anyone have any experience with either sizes? I also want to get the smarty tuner but can't decide which one to get... Either the jr or the s67me. Don't really have any experience with diesels and need some help.!! And also I plan on doing a few other things to it like intake mani and cold air but don't know any good brands or any feedback on anything!!