These things kind of sort of worked on cars back when they had carbs. Even then it was suspect. In theory, swirling the air could lead to better combustion and so on. But the issue is they put this thing in the intake before the TB and intake manifold so even if the air does start swirling, the flow pattern won't make it past the TB and what good does swirling air do when it enters the intake manifold? Exactly nothing since whatever flow pattern it had willl be broken up as the air is split into the runners for each cylinder. And the others are right, putting something in your intake will block airflow. The theory is better than some of the other junk out there like the fuel line magnet, but in the end this thing is still useless.