You may end up being disappointed. After 17,000 miles I have learned that I probably average 38- 40 mpg. If you are riding at 55- 65 mph in 6th gear, the bike is probably going to suck juice. The only time I am in 6th gear is 75 mph or greater for an extended period of time. I have the 4” Rineharts, Vance & Hines Power Duals, and FP3 tuner. Last year when I rode to Sturgis, I kept a mileage/fuel log and ended up about 40- 42 mpg.
One thing I have recently noticed: when I fill up and press the trip switch (left side controls),and scroll until the speedo displays ‘R’- which indicates how many miles remain in the tank, it will go to about between 187- 205, where it used to read 237, 240, 245 or so. Not sure what that means. Even when I fill up to the brim, the display will only go as high as 213 or so.