Hi,
Just to let people know, and if I did something wrong, please let me know. I decided to install a K&N cone filter on my S80 T6, and found that I had reduced performance. I got a big one, being that i figured it needed as much air as possible to be of any use. I got one that is about 8-9 inches long, and like 4-5 inches in diameter, with a 3 inch flange. With it in I found a considerable loss in acceleration. I monitored my intake air temp with my laptop, and found that it was about 16 degrees F. hotter, than with the factory airbox. I was once told that you lose/gain 1 HP for everyone 10 degrees of air, but it certainly felt like a lot more than a 1.5 HP loss. Plus, I figured that the 1.5 HP loss due to the temp would be made up by the more air, I guess I was wrong. Where the extra air was, I do not know, I did not experience it. I tried to watch the air flow on my laptop, so that I could see which one was letting in more air, but it was too hard while driving. Like I said, if I did something wrong please let me know. Otherwise, I just wanted to let evryone know so that you do not make the same mistake, and waste of money. Well, it was not a total waste because I am going to install it on my girlfriend's Audi A6 2.8 Quattro.
-J.P.