While this is kind of a repost, I will say it again... A friend of mine went from a $45 eBay CAI, to a namebrand ($200) on his P5. He's said time and time again don't waste your money. That there is no preceivable power difference between the two and the cheap eBay setup was much easier and less problomatic to install. Just my .02.
IMO, K&N want's WAY too much $$$ for a coupla' pieces of tubing w/a filter on the end of it. For what you get out of it in performance (not much) stick w/the cheapest route (-$$$) you can take.
In my case, I simply modified the stock airbox into a sort of SRI. Along with the exhaust it works great. Didn't notice anything astounding until the exhaust though.