If you can find out the correct point in the cluster, it should be a matter of changing the voltage, which will change the speed shown.
In the older R31 it's a matter of installing a potentiometer to replace a certain resistor in the cluster. That way you can adjust the calibration however you like. .. http://wiki.r31skylineclub.com/tiki-index....ter+calibration
I am not sure whether it will be so easy in R33, but you could look into it.