If you want to improve your Subarus cooling system pressure then you need to get this STi radiator cap.
This STi radiator cap came standard on the Subaru STi models so whether you need a replacement or wanting to upgrade your WRX radiator cap to 1.3 bar while adding a bit more pink at the same time.
More importantly, by raising the pressure in the cooling system you raise the temperature at which it boils allowing it to hold in more heat. Some Subaru models have 2 caps, if you are trying to improve your cooling system you will need to replace both caps.
This cap will not fit the BRZ/86.