Using your Noble rear diffuser is a breeze. First, unpack it from the box and make sure all the included hardware is there. Then, find the center of your rear bumper cover on your 2015 - 2021 Subaru WRX or STI. Use the provided hardware to bolt the diffuser securely in place below the bumper cover. When it comes to maintenance, keep it clean by washing it regularly with mild soap and water. Avoid using harsh chemicals that could damage the paint. If you notice any signs of manufacturing defects within the first year, contact us for warranty service. Remember, this diffuser is pre - painted, so be careful not to scratch it during installation or use.