It's understandable to want to see the EGTS of the "whole" engine, rather than just one bank. What if there is a problem in the right passenger cylinder bank, and you only have a probe in the left driver's bank? The right bank could be melting pistons, and you'd never know until the block windowed. So, your point of view makes sense. So does your mental math, where it is clear that you are adding another 300F mentally to your post turbo EGT gauge readings, where if the rule of thumb max exhaust manifold EGT's pre turbo is 1,300 F, you are limiting your push to just 1,000.
Still, 1,000F post turbo, "real quick", and "unloaded" at that... is rather high, even in high altitude. A new intercooler of the same size will not fix that. Not even the Hypermax Tapercore, at $1,775.00, which is inarguably the quintessential "intercooler upgrade" for the 7.3L, and which is undoubtedly the largest intercooler that will fit between the frame rails of a 99' up Super Duty, has enough additional surface area to bring that 1,000F down to something in the range of 600 post turbo unloaded. If the stock intercooler rejects 200 degrees, and the HyperMax TaperCore flows 30% more than stock, and for the sake of simplicity we ignore reality and blindly assume a direct correlation between an increase in flow through intercooler and an increase in heat rejected, then maybe we might see a 260 degree reduction in compressed combustion air temperatures.
Don't get me wrong, I'll take that 60 degree reduction... but I'm looking for a 400 degree EGT reduction. I know that the 60 degree reduction in intake air is not a direct number to number correlation, because the real benefit of a better intercooler is an increase in oxygen density per volumetric unit of air ingested, and the denser oxygen content will be a better match for all the fuel you are pouring in the cylinders with the Full Force single shots, tuning, high flow banjo bolts, bored out check valves, etc. And thinking about all that fuel... that would appear to me to be where the EGT problem is.
Yet, dialing back fuel may not be the only solution. Just because a person wants to lose weight doesn't mean they have to give up ice cream. There is obviously a reason you went through all the trouble to make sure your cylinders got plenty of fuel. The question of how much of that fuel is making power, and how much is being wasted in heat, afterburning in the exhaust manifold, and exiting the tailpipe as smoke is immaterial if you want ice cream once in a while.
So the questions that came to my mind when I read 1,000 degrees unloaded are:
1. What is your tire size?
2. What is your rear axle ratio?
3. What is your rpm when you hit 1,000 F "real quick" when unloaded?
4. Can you drop a gear when that happens?
5. Is your tire size and rear axle ratio putting you in a non optimal "automatic" shifting range for high altitude gear climbing?
Which brings us back to the location of your pyrometer probe post turbo... It is also "reading" the amount of heat that was converted to mechanical energy to spool the turbine. Yet that reading is muddied by both the volume of gas flow, and the velocity of gas flow, through that turbo. When you are unloaded, the exhaust flow is likely a lot less than when you are loaded, and in that case, the temperature differential between pre and post turbo pyros could be as much as 500F.
The variation in gas flow volumes and velocities through the turbo could be why people report that post turbo EGT probes are not as "accurate" or as "consistent" as pre turbo pyros. And if, in your case, there is 500 degree differential between pre and post turbo EGTs under some part throttle or unloaded conditions, where you were previously relying on a 300 degree rule of thumb difference, then at 1,000 F gauge reading, could you be pouring 1,500 degrees onto the tender tips of your turbine, turning the thin corners of the blade edges into a plasma that eventually vaporizes into the exhaust stream, leaving you with an unbalance wheel that takes out the ball bearing cartridge of your non rebuildable 38r? Ok, now I'm just fearmongering, not really helping.
I think if you are running a tire over 32" in diameter, you will need to manage your own shifting with your 4R100, no matter how built up it is. Do whatever it takes to elevate your engine rpms between 2250 to 2650 (the "50"s are just random additions to make this advice sound more credible), and that will be a much more immediate (and cheaper) way to reduce runaway EGTs on those hill climbs.... that is, assuming that you haven't already pulled that trick out of your already well worn hat, given that you live in the mountains.
If you are already gearing down to get the rpms screaming, then the questions turn back to the tailpipe. How much smoke? Tune the fueling back? Too much ice cream?
A new intercooler, however, would be much further down on the list of things to do. And if you do decide on an intercooler, most of them are simply lateral steps... to solve cracking or blown off plastic end tanks. I have a Banks intercooler on my truck... with high flow, smooth radius, solid cast aluminum end tanks. I'm not fond of plastic. But I'm not delusional to believe that a smoother flowing intercooler of only slightly larger size than OEM will reject so much more heat as and increase that much more air density so as to make a 400 degree difference in EGTs.
Yet if you are going to go all out, then get the Tapercore. No other intercooler on the market is larger, and the physics of a larger heat exchanger can be expected to have the capacity to reject more heat. The only issue for me many years ago was, the Tapercore intersects with the transmission cooler, whereas the OEM and Banks and I assume the Mishimoto intercoolers all terminate above the (stock and slightly larger V10) oil to air transmission cooler. Thus, I beleived the efficacy the OTA tranny cooler could be compromised. But that issue doesn't effect you, because you are running a 6.0L OTA transmission cooler (which wasn't invented at the time I installed a V10 cooler), and which is so much taller, it intersects with the OEM intercooler as it is. The Tapercore won't add much more of an insult to that injury, and experience has shown that the intersection of the heat exchangers hasn't cause measurable injuries anyway.
The rpm is around 1800 I know is low but when I shift to raise rpm it drops fast but to hold 60 mph it hovers around 900 on the TS Chip but on my hydra it would sit 800 unloaded in a light tow tune so I have gained some ground so from all the input for you all I think the best way to go is adjust waste gate have the tunes adjusted and move my pyrometer to the manifold.