How are the electric guys running their HV savox servos? Using a lipo rx pack or external bec?

I couldn't get my savox servo from glitching, it would twitch and move intermittently and I can hear it trying to center sometimes. This while using a Castle BEC set @ 7.4v. I ended up going back to my 7955tg, removing my bec and running it of my esc's bec. All is well right now, but I would like to get more speed and might give Savox another try.