Secondary fuel injection is applied to facilitate active soot management of the particulate filter within diesel aftertreatment systems, avoiding concerns with fuel delivery via in-cylinder post-injection. System performance is dependent on the thermo-fluid interactions of the injected fuel with the exhaust stream, with the intent of having more fully vaporized fuel and a well-mixed air-fuel mixture at the inlet of the oxidation catalyst for uniform thermal distribution as it exothermically reacts. Pre-heating the fuel with a diesel vaporizer prior to its delivery into the exhaust enables improved system performance, reducing droplet sizes and mixing demands. A diesel vaporizer is applied within the exhaust of a medium duty truck application, and the response of the catalyst is characterized across a variety of conditions. Cross-sectional measurements at the catalyst and filter outlet are described, including gas velocity, temperature, and HC concentration, and the effect of poor fuel vaporization is demonstrated. The system is installed in a medium-duty truck with a 4.8L engine and characterized on a chassis dynamometer across various steady-state and transient conditions. Performance is measured while applying closed loop fuel dosing control algorithms, demonstrating control capabilities similar to injectors. Adequate thermal distribution is achieved with minimal HC slip, and recommendations are offered to further demonstrate system integration benefits and risks of diesel vaporizers.