8 grand in sixth puts me around 75 mph, so I run in that neighborhood on the Interstate. I actually prefer to run between 6000 and 7000, seems to be less vibration and a little more ooomph when you need it.
Out on the real twisties(in WV), I like to keep them pretty high but they vary quite a bit(5-10.5). it helps when cutting into and out of sharp turns. Engine breaking is much better and its fun to really hear and feel it scream out of the turn.