Right now many guys are using the hitec 7995tg ( ~$90, 333in/oz ) or the nice Savox 1256tg ( ~$70, 270in/oz ), though there are loads of options really- some really nice HV servos around from Turnigy ( hobbking.com ) which are really cheap and powerful, just means running an external BEC to power them with ~7v of juice...