BLOX Racing Coolant Flow Upgrade Kit is specifically intended for the Subaru EJ20 and EJ25 left hand cylinder head’s #4 cylinder.
Longtime Subaru enthusiasts and tuners know the inherent cooling design oversight in Subaru’s left hand cylinder head, in the #4 cylinder, that always sees the hottest temps due to a lack of flow.

This kit helps to increase coolant flow to cylinder 4 and minimizes the overall risk of overheating and detonation, by drawing in flow from the water pump.

Applications
2004-2020 STi
2002-2014 WRX
2005-2008 Forester XT
2004-2009 Legacy GT