on the e36 people really mean a water ingestion baffle that is located behind the kidney grill. it is a total waste of time in my opinion and not worth the trouble. it is a part that does not allow water to enter your air box. why people take them out i have no idea there were tests done a long time ago that i cannot remember where i found them that showed no differance in the performance of of the airbox with that removed. and people who have tried it have said that it doesn't do anything. but i am going to get flamed by someone who is going to say that it is the best thimg they have done and their butt dyno shows 40 extra hp. to you guys i say to each their own.