An American tuning company has been slugged with a huge fine for “brazenly and repeatedly” selling emissions bypass devices for late-model diesel pickup trucks.

Idaho’s Gorilla Performance has agreed to pay a US$1 million fine (AU$1.55m) following prosecution by the under the Clear Air Act. According to the EPA, Gorilla Performance and its owner Barry Pierce bought and sold “tens of thousands” of devices and accompanying software designed to ‘delete’ emissions controls.

“The defendants in this case purposefully violated laws that protect air quality and the overall quality of life for Idahoans, especially vulnerable populations such as children, the elderly and those who suffer from respiratory conditions,” said Idaho attorney Josh Hurwit. 

While the EPA is winding down its major crackdown on aftermarket emissions bypass equipment to instead focus on toxic PFAS emissions, it announced earlier this month that tuner Sinister Diesel would be hit with a $1m fine.

These fines are far from the biggest handed down to diesel tuners, with the Diesel Brothers TV show hosts fined US$1.2m in 2020, and two Michigan tuners were hit with a huge $10m in EPA fines last year. 

A 2020 report from the EPA revealed around 15 per cent of diesel trucks sold new with emissions controls in the US have since had their controls illegally deleted, which equates to over 500,000 trucks.