I use to shift around 6300 because the needle is a little lagged and if you try shifting at 6500 you might bump the limiter. You are good anywhere from 6000-6500. I bumped my revlimiter to 6700 and I'm going back to 6500.
Cobra10th, it does hurt your car to hit your rev limiter,
but don't make a practice of it.
When you hit the rev limiter, I believe it cuts down
the spark timing and fuel.