If you really PACK the tank then you can get some great numbers. Me, I usually fill up right after (or close after) the fuel light comes on and I quit at the first click on the pump. Well, last night I "packed" the tank. I put 50 miles on mine today and it never moved off of over full. I am not trying to pop your bubble. It is just how you drive and how you fill your tank up (along with alot of other variables... tires, speed air pressure, foot pressure....)
If I can get some actual highway travel in there, I can get 320+ on a tank. Got 340+ last fall on the way to Cruisin' the Woods at Browns Camp. Had stock tires, but upgraded that trip to the Bridgestone Dueler AT Revos. Once the needle hits the last marker (typically after the low fuel light is on), I figure I have about 4 gallons left before I'm walking.
Only other mod I have is the set of Demello sliders.