Indy, 5,200# would be a "heavy 1/2T" if 6 lug, or a 3/4T if 8 lug .... and as said above, you won't improve the fuel economy beyond what can be achieved with proper tuning of the stock setup
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics
