Modded motors legal?

About a week ago, our team qualified to worlds and we decided to recustruct a lighter faster chassis. We quickly noticed a rule(R15) stating the following:"<R15> Parts may NOT be modified as follows:
a. Motors, extension cords, sensors, controllers, battery packs, and any other electrical component of the VEX Robotics Design System may NOT be altered from their original state in ANY way."
I did some research and found a q&a on the forums that states that “Changing the gears out of a motor with legal VEX replacement gears is an exception to this rule” please tell me which rule is correct, because in the rules it says that any answer in the vex forums should be taken as official ruling… I have put the link of the q&a here: https://vexforum.com/t/answered-393-motor-high-speed-configuration/20514/1

@StarStuck the ruling that karthik made is still the one exception to rule <r15>.
Hope this helps

<R15> applies to the electrical parts of the motors, as I understand it. Changing the internal gearing from (as my teams refer to them) from High Strength to High Speed to Turbo has always been allowed. Certainly as you go to a gearing that give you greater speed, you are sacrificing torque. So you need to make the choice that best fits your robot.