I use propane
I use propane injection. I also have a 100 HP programmer. I have a 7.3 and pull heavy loads. It lowers my exhaust temperature by 250 degrees going up hills, mainly because I can back way off the throttle and still maintain speed. Beware, if you start powering up, upgrade your torque converter and install a lockup programmer. I've been there, I'm on my 3rd torque converter.