Check my sig, I just finished 4000 miles with a 6000lb trailerwith alttitudes up tp 8000ft. Egt was not a problem if you watch the gauge on a long uphill pull and back off just slightly if they go too high, only had to do that 2 times and was still pulling strong just not accelerating besides 70 mph on a 6% grade I really didnt need to go any faster any way, just wanted to. The truck didnt hardly feel the trailer and I could use cruise control at 65mph on any grade and never lose any speed.