I use a K&N in my civic. I think it helps, but
I have also read that they don't filter as well
as they claim. Its worth looking into before
you invest the $60-100....

There was a thread on here I think about 2 months
ago that had a link showing the research. Can't
remember it though.

As for me? I will keep using it. I got a mileage
improvement when I started using it, and its saved
me money, plus its less landfill....

t