If you're driving a N/A and noise is a concern, then consider switching to a C240/320 intake. It provides 50% more breathing volume and uses larger filters without any added noise, plus it's plug and play and looks really cool to boot. Instead of the K&Ns, I went with the AFE Pro-Dry S air filters which don't require oiling, yet flow as good as the K&Ns and are also lifetime warranted. I picked mine up used from LKQ for under $100 w/ the front nose piece (the nose piece with the star logo is separate from the intake).

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Sorry for the dirty engine bay...can't pry the car away from the wifey long enough to clean her!
By the way, I've had this setup for a few years now (50,000 miles +) and recently pulled it off to check the throttle body and it was still pristine, so the filters work great!