This tune is rock solid above 20 MPG for sure. It is repeatable. The first test trip was from Riggins, ID where I filled and the to Donnelly, ID then to Lewiston, ID. I netted 28.04 MPG. This last trip I've gone 425 miles on just a half tank of fuel.
You must have a final ratio to the ground close to 3.73 gears. I'm 3.69:1 ratio with the 245/75 R16 tires (30.5 inches) I'm running. Injectors are +150 HP DAP VCO Injectors popped at 320 bar. I'm running a slightly bigger turbo HX35/40 hybrid. Drive to speed limt but no rocket launching from stops. Take your time building speed up.
425 miles on just a half tank of fuel. Not many can do this...
Hand math on the first test run.
Watch the elevation I'm not climbing or falling. It flat ground sample EGTs for 55 MPH.