To be fair, an 8v won't go much more after around there...
This is a standard engine graph

As you can see torque drops a lot, and after 5500rpm the HP falls too.
And now this is the same engine with a rally spec cacmshaft and some mods

Torque still drops a fair amount, but it holds peak HP for a little bit longer.
8v's don't really like to rev...
Generally when a mk3 cuts off at 5000 rpm it means it has gone into 'safe mode', have you changed the timing belt or had the timing adjusted recently?
If the limiter kicks in at 5000rpm then yes, but if it revs above then no...