High Performance Stage 2 Air Filter. The DNA Stage 2 Kit, can be either a DNA filter or a DNA cover that is designed to replace a part of the air box, seriously increasing air flow to the engine. With the proper fuel recalibration the results are always very impressive. This DNA®'s Stage 2 kit eliminates the O.E.M. intake snorkel and offers higher performance and better intake sound. This Stage 2 kit is designed to replace the stock air filter and the stock plastic air box intake cover. This Stage 2 product will increase the airflow, filtering efficiency, power, torque and throttle response. Installation of this new DNA Air filter is very easy; simply follow the installation instructions included in the workshop manual and the special instuction included with the product. The filtering efficiency is extremely high at 98 - 99% filtering efficiency (ISO 5011), with four layers of DNA® Cotton.