They do calm the wind turbulence quite well when at higher speeds. I used to have them inserted, but pulled them out last year to see if they'd make any difference, and they do. Will be reinstalling them this spring. The problem with them is that as Lil bastard says, there's a market for them on ebay, and so they get stolen. Here's a pic of what happened to a Boxster S owner in NJ who found this after returning to his car in a parking lot. They cut right through his top to take his windstops...
