If anyone wants to double up their aerodynamics...I have 2 of them for sale....lol....I have seen absolutely no difference....but, it would keep some the dirt out if you drove everyday...but I don't, and it only sees rain on the long trips....and not by choice....I romp up to 145 from time to time....no problems, don't notice anymore noise than normal...never had them on the vettes, camaros, etc....so, as Harbor stated to me a long time ago, they are there because MB doesn't want any droppings in their customer's garages....must be that valve cover leakage....anyway, I like getting more air into the engine bay, so they are off for good...as is the engine covers...why hide a perfectly good looking AMG motor...