I agree with Jbone that you can race with them, IMO the stock arms are the way to go. You have more tuning options with the stock, even more options if you use aluminum spacers in place of the one big black one. This also depends on what you will be racing on. A hard packed high bite track you will be able to feel the difference (even more with the carbon). On a loamy type outdoor track your not gonna get the same feeling the loose dirt will numb most of your finer adjustments.

I raced with RPM arms for months, the plus side is you will be hard pressed to break the arms.