JR 9100 series. Get the S for speed or the T for huge torque. Use them with Castle MMM and MMP, and tekin rs pro. No glitching problems with these servos. I tried a Savox 1258 with my MMP 2400 KV sc system, and it glitched like hell. Sold it and dropped in a JR 9100 T, and never had a problem.