The 10.5cm draw elbow that feeds the cable on top of the carb is what calls for a specially sized cable. You can replace it with the NT cable guide-bolt and that will allow you to use a standard cable if that is what you wanted to do.
Another thing is the quality of the cable. The RT cable is of lower quality to me, I replaced 2 before making the switch. Now, I have the RT carb setup with the NT cable and NT guide-bolt. A much tighter feeling throttle, and have not had to replace since. Hope this helps!