As someone who works in this industry: we do ECU modification and repair and as such, have regular contact with the EPA. Our products all align with all required emissions regulation and testing, which is why we're allowed to continue selling them. If the EPA says jump, we ask how high.
I say this because this cultural vibe of government agencies kicking in your door for doing innocuous shit needs to die already, that is simply not how this happens. We get letters, we get calls, VERY occasionally we get visits and said visits are scheduled weeks, sometimes months in advance. We always cooperate and the relationship, therefore, is not adversarial.
Honestly we have way more fucking problems with huckster vendors trying to fuck us out of a few extra dollars on parts than anything to do with the big scary government.
While we're at it, fuck coal rollers with a cactus.