getmadboy

Resurrecting the thread only because I had the same question and called K&N about it. The rep told me that the only difference was that the 57 series comes with the CARB sticker. Everything else is EXACTLY the same. If you happen to have a 63 series FIPK, you can still get a hold of the CARB sticker by filling out a form and taking a picture of the intake on your car or receipt of purchase. You must also take a picture of the VIN number on your door jam to prove that you have a 2.2L/AP2 (only the 2.2L is CARB certified, not the 2.0L) along with a photocopy of your vehicle registration.

http://www.knfilters.com/decal.htm

I hope this is beneficial for someone.