Wasn't aware of this thread (I usually don't post on these fourms very often) but I posted on another Jointed Rail related thread:
"Why not make a command in which we can run our locomotive in HEP mode, especially for passenger locomotives. Simply click the command, a pop-up will appear, and we can enter in however much RPM that we need to run. Then instead of the train idling with the idle_1.wav file (or n0.wav file for JR's advanced enginesounds), it instead idle's with whatever idle enginesound is used when it's at a certain HEP. For example, a P42 needs to run at 900rpm in order for HEP to work. We can use the command, type in 900 as the value, then it would idle with the notch 7 idle sound.
Speaking of JR's advanced enginesounds, I recently downloaded their RBMN locomotives and I was surprised to see that they added a startup/shutdown feature on their engines, as well as some much needed dynamic brake sounds (all of the trainz simulator games use the throttle sounds instead of dynamic brake sounds, which takes away from the realism imo). Although at first, the sounds ended up playing for only a few seconds and in increments, I was able to fix them by extending the dbend.wav, dbrake.wav, and dbstart.wav to 10 seconds and it sound almost perfectly. Just a suggestion but maybe upgrade all of the Jointed Rail locomotives with these enginesounds, as well as upgrading the enginesounds themselves to advanced? I'm aware that they only work with the jr_loco.gs script and not the fx_loco.gs script, as well as some config file editing for the locomotives, but it's still a neat idea. I was able to do it myself on my Amtrak P42, UP SD70M, and my BNSF SD70ACe on TRS2019 (though I sadly cannot modify any of the JR locomotives that are default on TRS2019). And hey, maybe add in the hep idea that I suggested."