Before you take them out drive a little bit aggressive for a week or two. I dont mean pedal to the floor but accelerating a little bit faster than you have been doing. I noticed that my mileage went up when I started giving more gas until I got up to speed then I would pull back the pedal to the point the power/speed are constant. I am also going off of a vacuum guage so I can get the cruising speed/pedal adjusted faster and more accurately.
I also know that the 1700-2200 is the most common rev range for my truck. All of the shifts occure about 1700-1900 under regular driving conditions. I usually see 1100-1500 after the shift though. It also looks like you might have installed them when they switch from summer gas to winter gas. That usually means a loss of about 1 mpg on my truck with the same grade from the same station. So I would leave it on there until summer for more even comparison. And fill at the same gas station. I can go to two different stations and get over 1 mpg better from gas station A compared to gas station B.
Bringing the temperature up to 200˚ might also help.
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