Description: 100% Brand New Color: Black 4 Cylinder Coolant Modifier for Subaru EJ Engines was designed to increase coolant flow to the #4 cylinder head area. The extra coolant flow helps lower the coolant temperature in the #4 cylinder and keeps it more even with the rest of the cylinders. This helps reduce detonation and knocking in the #4 cylinder, which are known to cause the dreaded EJ ring failure. Compatible with: Fits all EJ20 / EJ25 engines For Subaru WRX 2002 – 2014 For Subaru STI 2004 – 2008 For Subaru Forester XT 2005 – 2009 Subaru Legacy GT Package Includes: 1X 4 Cylinder Coolant Modifier, 1X T-Fitting, 2X Clamps As shown in the picture