Originally Posted by Maelochs

"Rolling coal is the practice of modifying a diesel engine to increase the amount of fuel entering the engine in order to emit an under-aspirated sooty exhaust that visibly pollutes the air.[1] It also may include the intentional removal of the particulate filter.[2] Practitioners often additionally modify their vehicles by installing smoke switches and smoke stacks. Modifications to a vehicle to enable rolling coal may cost from $200 to $5,000.[3][4]" (https://en.wikipedia.org/wiki/Rolling_coal)

"It is a violation of the CAA to manufacture, sell, or install a part for a motor vehicle that bypasses, defeats, or renders inoperative any emission control device."

Coal Rolling: What Is It, Why Do It, And Is It Legal?

Sorry if I messed up your fact-free zone.