The intake is a very sensitive part of the vehicle. If you ask a dealership, an aftermarket intake will void the warranty. Any faults with the intake, especially the filter, can cause total engine failure depending on what gets sucked in.
However, due to the Magnuson-Moss Warranty Act
http://www.impalaclub.com/naisso/magmoss.htm - the dealership has to prove that the aftermarket part caused the failure to legally deny the warranty. It doesn't mean that dealerships won't try to deny warranty coverage, but you do have
some protection.
I would recommend going with one of two intakes:
K&N, because of their Consumer Protection Pledge and Engine Protection Limited Warranty:
http://www.knfilters.com/warranty.htm. Here is the compatible one, which is CARB legal on the 08 and 09 models. I ordered mine from Amazon and it came with the CARB sticker.
http://www.amazon.com/69-7062TTK-Black- ... B002EIE3K4
The second would be the Nismo intake. It seems that one now exists for the later models:
http://www.ebay.com/itm/GENUINE-NISMO-2 ... 0916275027. This is obviously a rebranded AEM intake, which happens to now be owned by K&N. The part number is 16576-RNL35. Oddly enough, I have never seen this on the Nissan's website, so I would definitely call Nissan Consumer Affairs to find out if it a genuine Nissan part and whether it would void the warranty. If you're really concerned about the warranty and don't want to worry about swapping it out, check out this one.