The ECU (car's computer) is what controls the rev limiter. If you rechip your ecu you can (but its not recommended) get it to rev higher. If you rev much past the red line on a stock engine, it is likely that you will get "valve float", and this can cause a valve to smash into a piston. Also, without different cams, you will lose power really really fast when you go past the red line.
so basically if you want to rev higher, you will need:
A rechipped ECU
New valve springs, retainers, and possibly new valves.