The OEM Subaru head gasket is multi-layered steel. The OEM EJ20 gaskets have been shown to hold up under extensive boost pressures and high temperatures.
02-07 WRX stock head gaskets are .6mm (.023 in) thick.
Please refer to your drivers side door jam to determine the build date of your vehicle.
Warranty Disclaimer:Subaru of America will only warranty parts installed on a car that has a matching VIN to that part.