A pneumatic distribution system for an agricultural implement, including aplurality of fluid lines including a primary fluid line and at least twosecondary fluid lines, and atleast one header fluidly coupling the primary fluid line with the at least twosecondary fluidlines. The at least one header includes a header body having a fluid inletfluidly coupled to theprimary fluid line and at least two fluid outlets fluidly coupled to the atleast two secondary fluidlines, a top cover connected to the header body, an insert located beneath thetop cover andassociated with the fluid passageway, and at least one actuator operablycoupled with the insertand configured for moving the insert to control the airstream.
