I have been thinking about my '06 6.0 powerstroke also. It has 125k on it now and is not running as smooth as it used to. Maybe cause I ran out of fuel about 5k ago and had to jack with it for awhile before I got it to pick up again. Dash said 13 miles till empty and I was about 1 1/2 miles from the station I was heading to! DooH!!
Hasn't ran real smooth since.
I have already put an EGR delete and good studs and gaskets under the heads, so THAT problem is hopefully fixed.