3:73 just like in the signature, IC is MANDANTORY for boost above 10 psi IMO so far so good with mine on longevity front, even with the IC I self limit to no more then 12 psi boost sustained, unless I'm getting squirrely running empty.
Opinions vary about how higher boost hepls on EGT, it may, but there is more than EGT to be concerned with than just the coolness of the gasses in the chamber.
Prior life abuse for instance, I have high confidence mine was in nearly new condition when I bought it at 37K, truck had never been off road nor abused it was then in factory new condition other than miles, my 1st mod was gauges, and exhaust and I've lived to limits of 12 psi sustained boost level, and if post turbo egt gets around 900 I pull back and go a little slower, (it never goes over 850 running empty BTW even up to 115mph on the occasional journey up there).
I'm not sure of status of this particular vehicle but when QM 1st showed, he was running hard with no gauges, and really working the vehicle, he has made some changes since then, but if memory serves me he hasn't done a complete bottom up overhaul with new parts, I suspect there have been some of the "used but good parts" in the previous repairs which may have had some stresses in them. Even in this particular repair he is looking for a suitable single piston to effect a repair.
This is fine if on a budget, but one has to remember as D CAM points out as well; the rest of the train may have cracks, the ONLY way to KNOW balance of parts are safe for use are zero time replace or eddy current or some other form of detailed NDT (non destructive test) of components; visual or FPI may be good enough for a quasi rebuild for operation at stock performance levels but that would be my limit to pushing it.
I no way would I run "used but good" parts at performance levels QM has been running at, even a 12 psi boost I'd be wondering when it was fixing to grenade.
I'm in a quandry myself, I have 110K on the engine also a set of new 18:1 Mahles on the shelf hollering at me to be installed (these are Diesel Direct shave tops) I don't think they are "at risk" the way I drive (someday I'll install them just haven't made up my mind when), there may be a concern with the "shave tops" I guess some day I'll be the "lab rat" for those maybe I'll pull the working 21:1s shelve them and run the "shave top 18's".