Well spent all night look at all the youtube vids that went in to detail on how the grove is done! What I cant figure out is if it is creating a vacuum leak it would seen the engine would idle higher dont see that! Also has it hook up to a snifer and showing before and after changes in smog emissions I don't see how that would be possible! Last how is it that mpg increase after you open up the throttle the grove would no longer function may be part throttle would work. Just don't get the science behind this yet! The guys shop is a few mile from my house I may run buy and see what up!!