T600 120 inch sleeper fuel mileage

Dad has a 2007 ISX 475' 18 speed with 3.55 and a 20k front axle. Truck is 23k empty, bought it from Shelby Elliot in Sikeston. He hauls a 53' Shipshee plated for 80k, and hauls multiple camper trailers out of Indiana. He typically backhauls cars, trucks, and equipment back, can haul bobtail tractors, buses, etc.

When he first got it, it was getting low 7's and high 6's. Some improvements made were egr blocked, cooler blocked. During the Easter break, we swapped the original under cab muffler to a Donaldson M100463 from truckpro ($120, picked up at warehouse) and an Amazon turbo blanket for $120 I believe. We also used heat wrap for the two feet of exhaust behind the turbo before it dropped under the cab. He said after running the motor all day, you can hold your hand on the blanket and it's mildly warm. He usually runs about 65 mph and idles some using the winch to load, but the truck does have a generator for nighttime.

This past week, he ran out of Houston Texas to somewhere just across the border in British Columbia. Lots of two lanes, high winds, lots of 7,000 ft elevation in the mountains, and 7 percent grades. He got 8 mpg which has never happened before, and he said his pyro never got above 1000 degrees. The second tank in 45 mph winds, snow and rain he average 6.9.

These two improvements should pay for themselves within about two months easily. The only other mod we are going to do is the fuel pressure sensor trick with a resistor inline. Just thought I would share his experience so far, any improvement helps. Be safe out there.