My understanding has always been that the distance between the throttle valve and the combustion chamber is a factor in determining rpm efficiency.
Years ago in 125cc motocross we used to use a longer boot between the carb and the crankcase to increase the intake length, thereby increasing torque slightly. Today's auto engines have variable length intake runners to effect low and high rpm efficiency. But the intake length in question on these vehicles is adjusted after the throttle plate! (the primary intake restriction)