K&N air filter model?

[alternatefox]

Hey,
I keep hearing people talk about K&N filters, but nobody mentioned which filter they use. 
Is there a particular style that will just slide into the stock air filter box?  Or do you remove the airfilter box completely and put on a K&N filter as a stand alone?  I am interested in replacing my stock filter and get some better air flow.
Thanks,
J

[juice]

You will have to replace the stock air filter box and re-jet your carburator . Your scooter will also be considerably louder afterwards . Good luck .

[alternatefox]

I see...  Thanks for letting me in on the noise increase.  I like mine nice and quiet so I will pass on this project afterall.
Thanks,
J