I had an 06 until last year 170K mi, pulled a large boat but no frequent "heavy" towing beyond that. I never had more than injectors / oil cooler / turbo clean / glow plugs replaced.

I had a sct programmer on middle setting, but didn't hot rod it. I thought about it, but I did not do head studs.

You will probably go through more injectors, nature of the beast. You will most likely have the oil cooler and the egr cooler fail eventually. It is just a matter of time.

If it was mine, I would go with at least the bulletproof egr cooler or delete. At a min. Blow that and you could be talking at the worst hydrolock with catastrophic engine damage.

Head studs, maybe not so much, but if you have the funds you might as well.

Bulletproof oil cooler (expensive) but again if you have the funds, why not. Or at least change it out when you do the egr cooler. If it clogs with casting sand or other gunk from the block, your egr cooler will cook itself.

Somewhere in the process do a full coolant flush with VC9 to get rid of the casting sand / gunk.

A word of advice - Only Motorcraft filters all the way around, changing to 5w/40 and adding some archoil 9100 might help with the injector issue if it is due to stiction (you can try hot shots secret but it didn't do much for mine) archoil at every oil change got me through three years of "bad injector(s)" before I really had to change the ones that were failing. Continued with that after the change and ended up not having any other injector issues for the rest of the time I owned it.

Make sure they check your fuel pressure, and if low or close to low have them upgrade it to the blue spring (I believe it is the blue spring).

There were several FICM calibration updates along the way. One buzzes the injectors for a while when you turn on the key. This was supposed to heat them up a little / free them to help with the stiction issue. Didn't do much for mine, but you might want to check if all the calibrations are up to date.

While you are at it, pull the turbo and clean or change the unison ring, vanes and housing. I also think there is an upgraded oil feed or return line for the 03 turbo too.

Don't test drive a 17 or newer while having yours looked at, trust me.