I have an 05 Excursion Ltd 4x4 diesel. I'm currently running an SC max tuner (tow safe mode) with an Edge Juice platinum stacked(level 5 most of the time). I have the EGR disconnected (spool) and a Sinister Mfg. coolant filter. It gets 15 MPG mixed (according to lieometer) and 21 HW (cruise set at 75). Towing our 12.5K toyhauler it gets around 11. I am planning a 1500 mile camping trip and plan on doing the headgaskets and studs before hand. I need suggestions on anything else I should do while it's apart. (my mechanic is lifting the body). I am thinking about leaving the EGR cooler in place with the spool (there is talk of emissions testing soon). Should I replace the oil cooler, how can I tell if its plugged (ECT tends to be 5-10 degrees warmer than oil). I also wonder if the up pipe has the scoop and needs replaced. Also considering a larger pipe (turbo to muffler) and remove the cat. Also planning to go with an SCT tuner with custom tunes and EGR delete (tuner delete) after the studs are done. I don't want to just randomly replace parts unless I'm pretty sure they need it. The truck runs great, and to my knowledge has never had the coolant puking issue. It did have the FICM replaced under warranty in 2010. It is amazing how much power it makes and in such a large truck. It has no issues towing the trailer at 75MPH on cruise (Edge turned down to level 1) and has never overheated.
Any advise is appreciated.

 

Try asking in the 6.0 diesel section. By the way, sounds like you have a great X.