That's about what I've been getting.

Though on the track, it went up to 6.5 :)

In my FD with RB exhaust, no cats and no emissions, I got around 25MPG on the highway, and I got around 18MPG in town. AFRs were around 15 cruising and 12-13 under boost. I usually averaged around 325-375 miles per tank depending on how much highway driving I did.