Recent 2010 emissions standards for heavy-duty engines have established a limit of oxides of nitrogen (NOx) emissions of 0.20 g/bhp-hr. However, it is projected that even when the entire on-road fleet of heavy-duty vehicles operating in California is compliant with 2010 emission standards, the National Ambient Air Quality Standards (NAAQS) requirement for ambient particulate matter and Ozone will not be achieved without further reduction in NOx emissions. The California Air Resources Board (ARB) funded a research program to explore the feasibility of achieving 0.02 g/bhp-hr NOx emissions. This paper details cold and hot-start FTP thermal management requirements to achieve ultra-low NOX levels with a turbocompound engine. Additionally, the energy requirements of various aftertreatment configurations were explored and data will be presented to highlight the impact of turbocompounding on cold-start emissions. The fuel economy impact of engine calibrations, aftertreatment configurations and performance modifiers will also be discussed.