Originally Posted by outerdarkness

The idea is less smoke. Fuel is for converting to power. Smoke is fuel that did NOT get converted to power. Most of the trucks that do it have a multi-setting tuner set on the maximum race setting, but none of the corresponding improvements to airflow. Stupid.
That setting may say " + 200 HP ", but if you made no other mods, then you get less performance than using a lower setting that makes less smoke.
California has the right idea, they can impound your truck on the spot if they see coal, and they can then look for speed parts. If they find none, you're forced to fix the turbo and prove no more coal. If they find speed mods, they can crush the truck. Better to be responsible than have it forced upon you. I don't want my kids breathing the results of your failure to look cool. Why care if you're impressing anyone, especially anyone who can be impressed by THAT?