StevenH72 said:
The GruppeM never appealed to me, noise is great but nobody has really reported any other benefits. Pretty much every review / owner of the Eventuri has reported an increase in drivability and measurable gains........
I could go on in depth about the theory, development, tests, scientific rationale etc but I guess it would just be taken as "marketing spiel". So perhaps the growing number of people who are using the Eventuri and the consistent feedback they are giving is more powerful than the lecture I can give.
Another recent E46 M3 owner and his thoughts:
http://forums.m3cutters.co.uk/showthread.php?t=123648&highlight=eventuri