It’s no secret that the U.S. federal government has been on a years-long mission to find and punish emissions regulation violators. And it’s not just the large, high-profile, OEM manufacturers that they are after. We have watched as one after another of our favorite diesel aftermarket manufacturers and performance shops have been slapped with massive fines and criminal charges. The latest of these is Louisiana-based Power Performance Enterprises, Inc. (PPEI) and its President and owner, Kory B. Willis.

In March 2022, Kory Willis and his company both pleaded guilty to criminal charges of conspiracy to violate the Clean Air Act and violating the Clean Air Act, brought by a federal court in Sacrament, California. In addition to the criminal charges, a civil complaint was also filed in the Western District of Louisiana for manufacturing and selling emissions-delete devices. A $3.1-million fine was levied against Kory and PPEI.

The story didn’t end there, however. On December 18, 2024, U.S. District Court Judge John A. Mendez handed down final sentencing in the criminal case, which included an unprecedented 10 months of home confinement as part of a three-year probation term.

“For decades, EPA has prioritized efforts to halt the illegal sale of aftermarket defeat devices, which cause dangerous air pollution from trucks and cars,” said Assistant Administrator David M. Uhlmann of Environmental Protection Agency (EPA)’s Office of Enforcement and Compliance Assurance. “Today’s criminal sentencing punishes the defendants for their deliberate attempts to evade the requirements of the Clean Air Act and follows an earlier 2022 civil enforcement action addressing their misconduct. EPA will continue to leverage all of its enforcement tools and authorities to stop illegal behavior that puts our communities at risk.”

According to public court documents, from PPEI’s beginning in 2009 until 2019, Kory and his company were among the nation’s top developers of custom diesel truck tuning software. Of particular interest in this case were the company’s “delete tunes.” The documents also state that during this time, the company admits to tuning over 175,000 vehicles. PPEI records show the company was selling well over $1 million of product per month.

“Deleting” a diesel truck causes its emissions to increase dramatically. According to EPA testing, a fully “deleted” truck that has had all its emissions equipment removed or disabled increases NOx by 310 times, non-methane hydrocarbons by 1,400 times, carbon monoxide by 120 times, and particulate matter by 40 times. EPA’s Air Enforcement Division released a report in November 2020 finding that more than half a million diesel pickup trucks in the United States — approximately 15% of U.S. diesel trucks that were originally certified with emissions controls — have been illegally deleted.

According to calculations by the EPA, the estimated emissions impact of PPEI’s sales of delete tunes between 2013 and 2018 alone are expected to cause over 100-million excess pounds of nitrogen oxides (NOx) emissions over the lives of the diesel trucks equipped with those products.