check this out...
http://www.nismo.co.jp/catalogue/s15/cat10.html

I think NISMO know a thing or two on what they are doing...
anyhow...

 

I brought in my car for a 30,000 mile maintainence. My car has 29,000 but why not do it early, what the hell. Anyways they found out that I was using a K&N drop-in filter panel and then they told me not to use it. They said that Nissan engines are very sensitive to aftermarket products and blah blah blah. Then I asked him, "If what you're are saying is true, then why do I see modified Maximas that has more than an aftermarket filter?" He says, "Oh really, I don't know." After that he was telling me how the OEM air filters has their own unique oil in there. I believe that the K&N filter didn't cost me $50 for nothing. I know it's resuable hence the heavy price but there's always a difference in quality when one item is more expensive than the other.

 

The dealer is 100% right. The K&N does suck.(air that is!)
It also happens to suck better than most! hehe

 

Yes:

The K&N does its share of sucking:

It sucks in lots of air >> if the engine can pump it.

It sucks in lots of dirt >> until it gets dirty.... then the air intake downstream of it becomes cleaner >> because the dirt on the filter blocks more incoming dirt.

Either way, it sucks.... unless you got turbos or supercharging, or just a big super-size engine, a K&N filter won't make that much positive difference... probably negative in long term.

I'm looking for a CAI that doesn't use a K&N filter.

If you get more airflow with a Stillen type K&N filter or a CAI, well thats mostly because of the shape and geometry of that intake >> little to nothing to do with the actual filter material...

I hope NISMO "knows a thing or two" about what they are doing better than what STILLEN "knows a thing or two" about what they are doing...

Later...

 

I've had my K&N filter for about 70,000 miles now and cleaned it twice. The car gets slightly better mileage with it (maybe 1 mpg) and the power difference is not noticeable. But I'm saving money on not buying new filters every 15,000 miles! And my K&N cost $39.99

 

I feel the same way. My K&N probably doesnt give me any power, but I've saved money overall by not having to replace it.