People still play around but is it effective? have you ever been behind a kid in a Honda with a fart can spewing black smoke and stinking out the whole area behind the car . That kid is doing nothing but wasting gas because they dont know what they are doing and dint have the $$$ to do it right. Oh and it is illegal for emissions compliance in alot of states, I see cars like that and wouldn't pay more than scrap price for one of them after they have been screwed with and rendered jacked up mechanically.