I stumbled across this DIY boost control for Audis while looking for something else. I don't know anything about them except that this one was designed specifically for the Audi (ur)S4. http://autospeed.drive.com.au/cms/A_0670/article.html?popularArticle -- Kent McLean '94 100 S Avant, "Moody" '89 200 TQ, "Bad Puppy" up in smoke