A combine harvester includes a housing having a rear hood and defining an interior, a blower for generating an air stream in a substantially rearward direction, and a cleaning system separating residue from a crop material such that the residue is transported via the air stream rearwardly to be discharged from the housing. A chopper rotor assembly is disposed within the interior below the rear hood and includes a chopper rotor having a plurality of blades for chopping the residue as it is received via the air stream. A chopper housing is disposed within the interior and defines an inlet of the chopper rotor for receiving the residue and an outlet spaced rearward from the chopper rotor for discharge of the chopped residue from the interior of the housing. An air gap through which the air stream may exit the interior is defined between the rear hood and chopper rotor.