engine torque by turboprops

HiThe engine torque is coded in offset as a percent.But for example with the KingAir if you put the props in feather and push full throttle you obtain an overtorque, the torque gauge overpass the 100% to 120 %.My question, how to calculate the real torque, is there another offset which give the torque up to 100% is there a way to obtain it ?The kingAir Torque gauge is not XML, we can't edit it to see what offset is use for the display ...Thank'sBOBPS I aim to make an overtorque warning light