Features:

• A high-flow, washable filter that delivers the maximum amount of air possible into your engine while providing superior filtering
• Multiple layers of cotton fabric sandwiched between pleated aluminum screen capture airborne dirt particles
• Improves horsepower and torque
• Emission legal in all 50 states, will not void manufacturer's warranty
• Filters can be cleaned over and over, and are backed by a million mile limited warranty

Editor Reviews:

Product Description:
These reusable K&N Filtercharger air filters outflow any other filter--up to 900 cfm--for power gains of up to 15 HP. They use a surgical cotton fabric soaked in oil as their tack barrier. Sandwiched between an aluminum screen wire, the holes in the cotton catch tumbling air and straighten it out. Since air moving in a straight line flows faster, the filter actually improves airflow. They can be covered by up to 1/4 in. of debris before air restriction makes cleaning necessary. The filters come pre-oiled, and many are available as a direct fit for your application.

Rating : - KN Air Filter for my G35
I have noticed a little more power in the mid to high power range. Although I haven't seen an increase in gas mileage. It's to soon to judge the overall reliability and performance, but I am satisfied so far!