most people have no idea of what occurs in an intake tract. The vid I posted of the guy sticking his finger in the clear intake port also shows this. There are several quite powerful reversion pulses per intake(and exhaust as well) event that happen when a valve closes. Take a steel bar ,drop it on end and it bounces several times with each
being progressively less. That is exactly what happens when the air column(steel bar) slams into a piston(floor) before the intake valve closes trapping the pulse in the cylinder achieving possibly around 130% volumetric efficiency. The goal of a N/A engine is to capture the first and most powerful pulse at max torque OR max HP depending on application.If the valve timing is off,there will be those pulses exiting the intake along with the fuel.That is what fuel standoff is. All engines will have this happen at some rpm point.