I had a 2013 road glide 103ci with se204 cam loaded for touring and on cruise control at a sensible speed I could get 300 out of a tank although I’d usually be looking to stop from 250 onwards. I had a 2007 fatboy with an S&S 107ci top end and s&s 585 cams and cruising on the highway I could get at least 250kms out of it. Both bikes were properly dyno tuned with a se race tuner and tts tuner respectively. In comparison to your bike, something is wrong given your mileage.
Hey Jersey, no worries. when you changed the pipe did you just take the air sensor out of old pipe & fit it to the new pipe?