For the slightly less impressive BEC on the Hobbywing Justock ESC, I would actually suggest the low voltage Xpert 3000 or 4000 series servo. The Savox is a great servo but it can be hard on an internal BEC that is only rated for 6v like the Justock. Especially if it gets combined with Spektrum radio gear. With the xpert servos, they will run great even down to 4.8v and will have plenty of torque for 2wd buggy