I would like to comment on this since I am the tuner.
First off, the excursion is not responding to my tunes. I have tuned lots of excursions without issue. There are other behind the scenes items that are causing his issue. The truck has the fan come on with my tunes. Well I returned it to stock and the fan stayed on. The fan was staying on even though the signal from the PCM was 0%. That still tells me the truck has another issue. At that point I stated I did not have time to diagnose the fan issue (I don't work on trucks) and the vehicle would have to diagnosed by one of our techs. So it was determined that it would need to be rescheduled.
I was informed that after the owner disconnected his batteries that the fan issue went away. Ok, so I emailed him a stock SCT file, to see if it still stayed on even though I did no tuning. The fan still comes on. Well I don't make the base file, SCT does. So at that point it is either SCT's base file or something is wrong with the vehicle. It has nothing to do with if I can tune the truck or not.
Elite Diesel is more than willing to help our customer. Sometimes the fix isn't instant on an issue like this.
As far as 175's and a Powermax, Anthony was right, it will run hot at our altitude. Also you can't just tune down big nozzles at altitude. Ask Aaron Rudolf if he has a newfound respect for altitude. Clean trucks everywhere else, smoke up here.