Couple different links I was provided when I was looking at a K&N or CAI kit
Data showing how K&N actually flows worse than a stock filter, but allows a lot more crap into your engine. K&N Air Filter Review - Debunking the Myths (and why OEM is better) ISO 5011 Duramax Air Filter Test Report
Remember, your car already has a CAI kit. Its housed in plastic box, with air being directed right into it. You only needed a CAI kit when you had a your air filter sitting on top of your engine and the only air it got was the warm air circulating under the hood.
Video showing CAI is bunk. They even put the filter outside the car in front of the fan. https://www.youtube.com/watch?v=gCi2yo4UqPI
Video showing how those bigger air filters like K&N dont do much of anything on a dyno either https://www.youtube.com/watch?v=PAIxeQUSg-Q
They look pretty, but they dont do anything for you. If anything, you might be hurting your car's HP