snake oil.......one bloke has tried it on his briggs and stratton lawn mower engine via hacking a groove with a 1/4 inch file, and reported it now uses a 1/4 of the fuel and idles much better
........surely thats a credible enough thread for all us and all big motor manufacturers to jump on board!.........but joking aside, if someone like briggs and stratton said "yep, we''ll have it" you can have 10 cents royalty per engine, he will be a very very rich man........their engine production volumes are well into the millions.
but seriously, I think he has something, it seems to work better on some engines and not so well on others, main benefit is improved idle behaviour and emissions.......with small improvements in mid-range and max power.......I think its best suited to high compression race engines with big piston intruders that mask the other side of the chamber.
it would be interesting to see how it would perform on a highly strung 2-valve motor like a nascar engine........we shall see