When you press the X button you have 'super' speed(usally on MP). To deactivate this mod press the Z button.When you doesn't work then press first the Z button and then the X button (Sorry for My bad English bit I'm Hungary)
I FOUND HOW IT WORKS!!:
use it on a superman mod...
press "X" to accelerate
press "Z" to slow down
i guess i just saved you but you hungarian guy
it seems that i know how to use your mod better than you!!