I bought this along with the filter cover and just from driving it today I notice several things. First, when my vehicle is idling it is much quieter. Second, I noticed that the throttle is much more responsive. I have an exhaust on my vehicle as well so I cant say I can hear the air getting sucked in but I'm not complaining. This definitely clean out the clutter that the stock air intake was taking up.
Nissan Altima CAI
The AEM CAI System for the Nissan is a very well-built and quality product. This is my second AEM Intake system that I have installed and I believe the the instructions are very clear and detailed for each application. It is also very nice to know that I have a solid company like AEM and AutoAnything behind me if needed.
Installation was really easy, took a little over an hour for my brother and I to do it, and we are far from experts. The throttle response does seem to be a bit better. The car seems a bit peppier. I have not noticed any fuel efficiency gains at all. There is a noticeable change in sound. I wasn't really looking for that, though I figured it would be that way. Of course it's louder when you floor it, but it's also noticeably louder from a stop with "normal" acceleration. Up to about 2000 RPM.