The guys over at Team Novak are always a helpful bunch, and the other day released a helpful guide showing their recomendations for ESC and Motor combinations for the Axial Racing lineup of vehicles.
If you are in the market for a new system for your Axial rig it is certainly worth checking out at http://teamnovak.com/file_download/1405096973Novak_System_Recommendations_Axial_%28web%29.pdf