there is a 520 kit on e-bay right now. i think some of the high power guys are staying with the 530

 

You may be surprised. Alot go with the 520 to lighten up their bikes. Less rotating mass makes a differents from all that I have seen. And Hubbies bike is no slouch by any means. Had quite a bit done to it last winter. But my new Raptor has a 530 on it but I would say that is for torque and quite a few ponies reasons.