Balls to the wall has a different etymology. It implies pushing a throttle lever all the way forward. An airplane version of “pedal to the metal”. “Balls out”

Balls to the wall has a different etymology. It implies pushing a throttle lever all the way forward. An airplane version of “pedal to the metal”. “Balls out” and “balls to the wall” are two different technological metaphors with the same general idea though (going at top speed).