If it ain't broke, don't try to fix it. As a racer at the ONLY raceway in Florida that runs My Series rules in four classes and weekly or bi-weekly races running these rules in those classes, I'll say it ain't broke. The Hawk 6 with the stock Chinese arm is probably the most reliable and economical motor run in any of the classes. For $18 you get a motor, that with very few mods other than springs, brushes, and a comm cut, that is competitive right out of the bag if setup properly. That motor setup, with maybe one or two replacement arms off the parts wall, can last you a whole race season if treated right.
We run LMP/GT-1 every week with this motor, and have very few motor failures. We run this motor in Group F every other week with very few motor failures and the motor is fast. The JK ready built car out of the case with this motor and a simple gearing change is competitive. Why do you feel the need to replace a good performing cheap arm with a Pro Slot arm that costs almost $30 that may or may not perform as well? You can get two to three comm cuts on the stock Hawk 6 arm. You will literally weaken the magnets in the setup before you will destroy the arm usually. Not to say they don't throw winds, because any arm will, even American made arms. You run the stock arm for a couple of races, send it off to be balanced, then put it back in, and you are good to go. I ran one of these motors for a whole season in LMP at Jax and was the lap record holder for awhile. It didn't come out till the end of the My Series season.
This "motor change" has already been suggested and done when they fubared and allowed the Big Dog arm to be put into the Hawk 6 setup for GTP. That was done at a suggestion by racers who participate at a track who don't run the class on a weekly basis and also supported by the "Tech Director". What that did was obsolete the S16D motor program that many of us had who actually run the class. Very hard to compete with a motor that makes the car 12 grams lighter, so many of us had to start a whole new motor program to be competitive with lighter cars. Let me tell you, the Big Dog arms are no where near as consistent as a "Big Block" (.560 dia.) S16D arm. At that "Tech Directors" track, they maybe run GTP every couple of months.
In short, I repeat, it ain't broke, it don't need to be fixed. If you feel the need to built extreme motors with American arms, we have the NASCAR class with the FLA 16D tagged arm, the GTP class with the Hawk6/Big Dog fiasco, and Group 12. Leave the LMP/GT1 class and Group F classes alone. They are working fine. "Nuff Said.