If your computed torques are out of the range for your robot, then youryou are no longer modelling your robot but a different one. You can ignore the torque limits as good as the joint angle limits of your robot (i.e. not at all). If the required torque is to high, your robot will either be much slower (if you are lucky) or won't be able to reach its goal positions (e.g. if it's just not able to overcome gravity).