These genuine OEM Subaru gaskets for the Subaru WRX and STi, are used between the intercooler and bypass/blowoff valve. Because this is a pressurized connection, a worn or cracked bypass valve gasket can result in a serious boost leak and may even lead to more serious conditions that can damage your engine. It is important to inspect and replace these gaskets from time to time, especially if you have purchased your WRX or STi used.