the theory behind a boost bottle/chamber is that when the intake window on the crank shaft closes (located under th carb throat) the inertia of the incoming air/fuel mixture has nowhere to go and stops dead and kinda bounces out of the carb opening a little.
the boost bottle hooked into the carb throat under the main body of the carb acts like an accumulator in the way of soaking up the incoming air/fuel mixture keeping it from stopping dead and keeping the speed/inertia going and taking the work away from the vacuum created inside the engines crank case, in turn freeing up horse power and torque, helping idle and tuning.
of course this IS just a theory.