Using your Injen cold air intake is straightforward. First, make sure your Subaru WRX engine is turned off. Remove the old air intake system and then install the Injen intake following the provided instructions. It's designed to work with the stock calibration, so there's no need for complex adjustments. When driving, enjoy the extra power and the cool intake growl. As for maintenance, regularly check the Injen SuperNano - Web dry air filter. If it looks dirty, it can be serviced according to the filter's cleaning guide. Also, inspect the stainless steel band clamps and silicone couplers from time to time to ensure they are in good condition. Remember, this intake comes with a limited lifetime warranty, but always follow proper installation and maintenance procedures to keep it working at its best.