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You already have the X-51 dual intake air box on your 40th. IMO, CAI increases only the air intake sound and thereby the driver "thinks" it increased the HP. Some will say that the CAI will allow the engine to rev more freely, but even if that is true, that in itself does not add HP. Most CAI actually pull some of the air from the hot engine bay, unlike OEM. Some companies claim a 10 to 15 HP gain from just the CAI. If it was that easy, don't you think Porsche would have done this years ago? Oh yeah, if you use too much oil on the filter it could cause a problem with the MAF, or damage the MAF.
IMO, not a good bang for the buck, especially on a car with the X-51 package. Others may, and probably will, disagree.
+1
Besides K&N sucks.
Just put in a BMC F1 cotton filter and call it a day. $80 online.