Where are the spark plugs on a 2003 Subaru Imperza WRX?

The spark plugs on a 2003 Subaru Impreza WRX are located on the top of the engine, under the intake manifold. You'll need to remove the intake manifold to access them. This is not a simple job and requires some mechanical knowledge and tools. It's not a DIY task for someone without experience working on cars.