That's not the rev limiter.. the rev limiter only stops you from going into the RED zone, I know I've hit it on my car before..

Its probably just the motor running out of air on the higher gears, its always easier to hit the redline in 1st and 2nd and maybe 3rd, after that you don't really need to hit it, as you'll never really reach the redline unless you're reaching top speed. For this you'll probably require a nice long straight road. (cough cough! 401 cough!

)
I had my car at 205km/h and I was probably hitting 7000 or so, never really payed attention as I was more concerned about the road ahead than about the speed my motor was at.