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 includes a roof structure located above the chopper rotor such that a minimal gap is defined therebetween. The air stream flows out of the interior via a flow path defined through the chopper rotor without being substantially redirected from flowing in the rearward direction by the plurality of blades of the chopper rotor.
