The hell is the difference between 57 and 63 series K&N?

[SRT-11]

just like the title. i'm looking to purchase a K&N, and I could give a rat's ass about "CARB approval" seeing as how florida is so bad ass

so what's the dif?

 

[Craig]

63 series is what I have, I think.... lol now that I look on K&N's site I'm not sure and I don't recall the p/n anyone sure on this????