Header, Intake, & Exhaust - intakes?

Hi can anyone tell me about cold air intakes. I am thinking of getting a k&n 57i induction kit for my car. Is there any differences between the k&n and the cheap ones on ebay. I dont want to sacrifice quality for price.

the main difference is the quality of the filter. If you buy a cheap one off of Ebay, just get a nice filter and it will work just as good. The piping is piping... the filter is what wakes your intake.