How do you put a federal emission engine in my 1999 subaru impreza car with California emissions?

To install a federal emissions engine in your 1999 Subaru Impreza that originally has California emissions, you'll need to ensure that the engine swap complies with local regulations. First, remove the California emissions components, such as the EGR system, and replace them with the appropriate federal emissions parts. Additionally, you should check with your local Department of Motor Vehicles (DMV) to understand any necessary paperwork or inspections required for the swap. It's also recommended to consult with a professional mechanic or emissions specialist to ensure the installation is done correctly.