When I first got my SEGRU I did not get good milage. It was around 180 miles and would take 5.4 to 5.6 gallons. Much worse than the other CVO's I have had. As the miles got put on the milage went up, around 200 miles a tank and the same amount of gas.
With about 3500 miles on the bike Doc in FL tuned it, with my fullsac 2.25 baffles and fullsac head pipe and the TTS Tuner.
I avergage 220 miles per tank now at 5.2 gallons.
Trip I just did to FL and back with very little interstate but good 4 lane at 65 mph average I was getting 230 miles per tank and 5.1 gallons. So right at 45 mpg. Out west running 80mph I would get 200 miles per tank and 5.2 gallons about 38.5 mpg.
Much over 70 mph the gas milage goes away fast.
That said my CVO King with the built motor, head work, pistons, injectors, throttle body and cams and so on, gets much better mpg. Running 60 to 65 I average 49 mpg and a few times over 51 mpg. I have gone 270 on a tank in that bike. Again tuned by Doc.