Diesel Bombers - RV275 Bosch injectors installed but loss of MPG

I could use some help guys! I just recently changed out my stock injectors to the rv275s and I lost a good chunk of mpgs, I was getting about 16.5-18 highway at 75-80 mph but now I’m down to 11-13 highway at the same speed. I have tried two tanks of fuel and gone easy on the pedal and tried to do 70-75 but still no increase in mpg. While is was doing the injectors I also added an aftermarket air plenum to help with the egts and trying to keep them down. I have about 140k on the truck so I did the injector upgrade. I also did a brand new fuel filter at the time as well. (It was time for oil, fuel, tranny filters and changes anyway) I have an airtex 3157 or something like that lift pump, in tank pump that’s stock, big line kit from filter to VP, fuel pressure gauge and its steady at 17-19 psi at idle. I’ve got an Edge EZ tuner (which is why the rv275s) heard it was a great powerful yet good mileage truck for a daily. The truck has the following mods: S&B cold air intake and air horn, edger EZ tuner, big fuel line kit, airtex lift pump (have a fast ddrp just not installed as the airtex is still pumping 17-19 psi) air manifold plenum, timbo apps, noise isolater for torque converter, gauges for FP, EGT trans temp, 5 inch turbo back exhaust, deep tranny pan +4 quarts more than stock,and the rv275s. Anyone know why I have dropped so much mpgs?

Also I made sure that I did the install properly I tightened down the injector last after the tubes and lines were all connected and tightened to torque as I was told that was super important to look at and not mess up. I’m just stumped as they came in a blue Bosch box and the part number was correct but I can’t figure out why I have lost that much mpgs. I could really use some input, do I get a bigger turbo? Go back to stock injectors? I really like the addition but the fuel price is hurting the pockets. Any help or advice is very welcomed!