9,000 rpm does equate to right at 83 mph (right on what your speedo is showing). If your Rebel can do 83 mph on flat level ground with stock gearing, that is a top running Rebel. Not doubting it, just saying, if so, your Rebel is on it's "A Game."
I haven't top ended mine yet. I need to find some flat level ground so I can do some "research" when I get the AFR gauge up and running and then start tuning. I'm thinking of 2 tests. 1) A timed 5th gear 50 - 70 mph pull, before and after tuning. And 2) top speed, before and after tuning. Gonna need a loooooooooong flat stretch for this. Don't know any that are long enough around here.
2016 Honda Rebel 250 - The "Piglet."
AFR sensor equipped and downsized to a 0.105" main jet.
The only changes so far.
Bought on 6/29/19 with 44 miles.