An exhaust after-treatment mounting arrangement is provided that is mounted outside of an engine compartment and has a perforated enclosure allowing air to permeate the enclosure and establish an airflow through the enclosure to maintain part integrity of components of an exhaust after-treatment system with maximum temperature thresholds. Components of the exhaust after-treatment system may be mounted to permit movement of such components relative to upstream and downstream components in the exhaust system. The enclosure is configured to prevent contact of the hot components by operators and/or flammable materials with small venting holes through top surfaces of the enclosure and large vent holes in bottom areas of the box that allow large volumes of air to easily flow into the enclosure.