IAG Performance Cylinder Head Threaded Plug Set of 8The Subaru FA20 cylinder heads use pressed in freeze plugs from the factory. It's common for the plugs to fall out, lose coolant externally or even internally into the oil. Unfortunately, most of the freeze plugs are located behind the timing cover and valve covers, so you would never know if they popped out. This can happen on OEM cars as well as cars with performance upgrades causing a number issues that could be catastrophic. To solve the issue,