The rev limiter is probably at 6200 although it could be at 6700. There really isn't such a thing as too much rpm as long as theres a load on the prop. The rev limiter on mine on the Hydrostream is at 9000.
I beleive it is 6700 as both motors are using CDI power packs and there site is listing it at 6700. Dhadley would it be O.K. then to run up to the rev-limiter if it is possible, the motors are stock.