Invidia's turbo outlet for the 03-06 Evolution 8 & 9 is designed to bolt up to the stock turbo and will mate to your stock or most any aftermarket downpipe. The Invidia design features an improved inner diameter for better exhaust movement and improved spool. The Invidia turbo outlet is also referred to as an O2 housing. Invidia's turbo outlet is made of cast steel for excellent heat resistance and heat dissipation. The low price and the significant increase in performance makes the Invidia O2 housing an upgrade that is hard to pass up for any Evo owner.