Diesel engine NOx emissions requirements have become increasingly stringent over the past two decades. Engine manufacturers have shown through the use of EGR and SCR technology that these requirements can be met. However, the desires for improved fuel efficiency, lower overall cost, and potential legislation to reduce NOx levels further increase the demand for higher DEF dosing rates. To meet this demand, a new DEF mixing technology has been developed.This paper describes the development methods used to create a compact, in-pipe mixer which utilizes an optimized wire mesh along with swirling flow to permit high DEF dosing rates without deposit formation. Its excellent mixing characteristics allowed for high NOx reduction to be achieved. Utilization of this technology makes it possible to reduce regeneration frequency, reduce the overall size of the SCR system, possibly eliminate the EGR system, and improve fuel efficiency through combustion enhancements.