The redline is 8,000 rpm and the fuel cutoff is around 8300. The engine peaks power at around 7600-7800 so there's not much benefit above that. Watch raising your rev limiter without upgrading your valvetrain as you can float a valve and destroy your engine. Also, once the hp peaks, there is little benefit going past that point, so 8000-8300 is best. Seeya.