Collection enhanced materials, flue gas additives, and methods of making the enhanced materials and flue gas additives are provided. In one embodiment, a down stream addition system configured to control material passing through a metering device from a vessel to a gaseous exhaust path extending between a unit and an exhaust flue of the unit is provided. In alternative embodiments, methods are provided for introducing at least one of a flue gas additive and a collection enhanced material to a gaseous exhaust stream exiting a unit; exposing and removing at least a portion of at least one a of flue gas additive and a collection enhanced material from a gaseous exhaust stream exiting a unit prior to entering an exhaust flue; and recycling at least a portion of material removed a from a gaseous exhaust stream exiting a unit back to the gaseous exhaust stream without passing through the unit.