Using your Injen Evolution Cold Air Intake is straightforward. First, make sure it's properly installed on your 2015 - 2021 Subaru WRX. Once installed, just drive your car as usual and enjoy the increased horsepower and torque. When it comes to maintenance, regularly check the air filter through the Injen Clear - Vue Window. If it looks dirty, remove the filter and clean it according to the instructions provided. Keep an eye on the silicone couplers and band clamps to ensure they're tight and in good condition. Remember, this intake is designed to work with the stock calibration, so there's no need to make any major adjustments to your car's settings. Also, avoid any rough handling that could damage the intake's components. With proper use and maintenance, your Injen intake will serve you well for a long time.