I am towing 8000 pounds of boat and trailer from San Diego to VA. Today pulling up the mountains to Flagstaff, the post turbo (about 6 inches from the joint) EGT gauge kept going to 1200*. The temp was 102* air temp with the water temp gauge touching 235*. I assume the loud tire noise that kicked on and off was the fan. Why does it wait so long to come on???? I keep decreasing the speed and running the heater to help it. Its running the Predator tow tune (which says in the manual that its within GM specs) and a 4 inch turbo back. I am really upset with the quickness of this motor to overheat. I pulled the same boat with a 1500 4.8 5 speed flat on the floor over 4500 rpms for minutes over all of these hills with no temp problem at all! Also, the engine light is on for EGR but I was told it was ok for now because I didnt have to block it. I am killing this thing??????