I have one in my VW Passat GLS. Supposedly helps get more air into the the (small 4 cyl, large turbo) engine. For VW/Audis, K&N's are highly suggested if engine mods (chipping) are to be done. With my engine stock, the benefits have been very minimal. It may have smoothed out some of the turbo lag and powerband. They usually cost about $40-$50 & last a long time. You clean and reuse every year or so.
Don't have any plans on purchasing one for the Pilot, unless others have great success with them. I have noticed the slight "flat spot" in the powerband that has been mentioned in some of the car magazine tests. Dont' know if more airflow would make a difference, and not really worried about it at this point.