You didn't answer how much you wanna spend yet. The recommendations weigh pretty heavily on your budget. Best middle of the road option is probably one of the A81 servos from AGF. You can decide whether you want torque or speed to be more important. I recommend running at least a
Glitch Buster if not a 2s lipo receiver pack or external
BEC if you still have stock ESC. For saver you can generally go Hot Racing or whatever other amazon knockoff like Sharegoo, they will all be better than stock.