About three months ago I installed K&N OEM replacement air filters. Before this I was getting about 20 MPG in town. Now I'm getting 18. Anyone else experience a drop in mileage with K&N?

I searched the K&N website and they make no claims about mileage, just performance. To tell the truth, the car does seem to be running stronger.

Just wondering if this is my problem or I should be looking elsewhere.