I'll get anything that doesn't have mechanical stops on the timing adjustment. (And used, since I'm cheap!) The Novak Ballistic comes to mind (as Raman uses), but there may be others. Advancing the timing far enough to get the same top speed as a silver can will reduce the efficiency and power output, but it should still be quite sufficient. However, it is very hard on the ESC, as the ripple currents go way up, so one needs to be careful.