This kit will fit the 2005-08 Roush supercharger kits. This kit does use the 90mm mass air housing w/ custom adapter plate for 2005-08 application. This kit adds a 2.57 pulley and 90mm idler. The pulley will result in 7-8 lbs of boost total. Stock roushchargers are seeing 4-5 lbs of boost. The billet idler is needed so that you can reuse your stock roush belt. This kit will need a custom tune. Adding this kit will void the Roush 3 year 36,000 mile warranty. We recommend using the Autolite HT0 plugs with this kit. This is the most you can do to a roushcharged car without upgrading the stock fuel system.