Using the Injen cold air intake is straightforward. First, make sure your engine is cool. Locate the existing air intake system in your INFINITI G35 and carefully remove it. Then, install the Injen SP cold air intake in its place, following the included instructions. When it comes to maintenance, regularly check the Injen SuperNano - Web dry air filter. If it's dirty, clean it according to the cleaning guide provided. It's important to keep the intake tube free from any debris or blockages. Also, make sure all connections are tight to ensure optimal performance. As for the warranty, keep your purchase receipt as it's needed for any warranty claims. If you notice any issues with the intake, contact Injen's customer service right away.