Between July 1, 2015 and December 21, 2017, Holderdown Performance, LLC (Holderdown) violated Sections 203(a)(3)(A) and 203(a)(3)(B) of the Clean Air Act by removing and/or rendering inoperative the exhaust gas recirculation, diesel oxidation catalyst, diesel particulate filter, selective catalytic converter, and/or on-board diagnostics systems and selling, offering to sell, and/or installing parts and components where a principal effect of the part or component was to bypass, defeat, or render inoperative these emission controls and emission-related elements of design on heavy-duty diesel-engine trucks. EPA uncovered these violations through a Request for Information issued under Section 208 of the Clean Air Act on December 18, 2017, to which Holderdown responded on March 23, 2018, May 22, 2018, and July 11, 2018. EPA issued a Finding of Violation to to Holderdown on September 28, 2018. Holderdown confirmed that it is no longer removing, disabling, or bypassing any emission control system or element of design on any vehicle. Mr. Holder certified that as of January 2018, they have not had, and will not have, any defeat device(s) in their inventory and/or possession. Mr. Holder has agreed to pay a penalty of $7,500 to settle this action. These violations resulted in approximately 41 tons of excess annual nitrogen oxide emissions and 682 pounds of excess annual particulate matter emissions.