I've decided I have to get a K&N air filter after test driving for a little while with the manifold to the turbo removed. Oh my goodness, what a beautiful sound the turbo makes; I can't beleive what I've been missing. The K&N is a must simply for that enjoyment. So what if it decreases my engine life by 3 percent. Look at this link, the K&N filtered pretty good. http://www.bobistheoilguy.com/airfilter/airtest3.htm