The Impreza WRX STi was the high performance variant for the Subaru Impreza. Using the Impreza WRX as a platform, the first generation WRX STi featured a raft of improvements such as improvements to the transmission, suspension, and engine. The STi, meaning Subaru Tecnica International was fitted with a turbocharged flat four engine, and was only offered for the Japanese market. Production of the first generation Impreza WRX STi continued until 2001, when the Second Generation Subaru Impreza WRX STi was introduced.