Air tools are fine -- after the car left mechanic's garage, I cannot tell if air, electric or manual tools are used. But if I give my car to mechanic for carb

Air tools are fine -- after the car left mechanic's garage, I cannot tell if air, electric or manual tools are used. But if I give my car to mechanic for carb cleaning and tune-up, and get it back with fuel injection system and explanation "it is better anyway", I would be very unhappy.