Using the Invidia G200 cat - back exhaust is simple. First, remove the old exhaust from your 2002 - 2007 Subaru WRX or WRX STi. Then, install the Invidia G200. Make sure to use the new gaskets and hardware that come with it. The exhaust hangers are already welded at the right spots to fit your car directly. Once installed, start your car and enjoy the improved sound and performance. Note that if you're using the factory downpipe, you'll need to get a cat - back adapter. For maintenance, regularly check the gaskets and hardware for any signs of wear. Clean the exhaust tip with a mild cleaner to keep it looking shiny. With proper use and care, this exhaust will serve you well for a long time.