Stock? Some of it is stock! 2007 F350 only has 36000 miles (yes that is thousand) Found this great truck in late 08 when diesel went above $4/gallon. Knew the 6.0 historically had issues, so I saved up some money and started by changing out the exhaust! 4" MBRP turbo back/cat delete kit. Sounds awesome and lets it breath.
I then saved up even more and found an ex ford diesel mechanic who replaced the head studs with ARPs. And deleted the EGR. I got a SCT tuner and purchased a few tunes from some reputable guys and my truck pulls like a scalded mule! The tow tune with turbo break is awesome when pulling my 15K+ fiver. Just hope my state don't start checking for all the emissions!
It is amazing what you can do to a diesel to get better mileage and power!