Or you can just costume make one yourself like i did.
The only diff b/w all the ones mantioned above, like said above, is that knn has the heatshield.
I find it quite boring buying things and just installing them. I like the thrill in making my own work and etc. CAI are very simple. They are just straight piping that allows air to flow to your engine easier. They are all made tha same size as your stock Intake, width of 2.5 in. And all it does is that it takes out all the turns and bends that are made on the stock intake which also help reduce some noise. The CAI will give your engine a nicer, sorta deeper hum to it, and it makes it look better.
If you go a couple of pages back you can find the DIY thread i wrote and you can make your own CAI for about 150$. Its easy to make and very fun.

and it works fine, improves mpg and it give the car a lil extra kick. But like everybody knows, CAIs wont really give you any power, just the sounds it makes will make you feel like you're going faster. haha. gl