Ditch your stock FR-S cap for a finer cap. The fortified main pressure valve spring and silicon packing are used to raise the pressure inside the radiator for a higher boiling point and less issues on your track day! Coolant will not boil as easily, air bubbles in the block are reduced, and your car will stay cooler as a result of increased heat transfer. Cusco's high pressure radiator caps works at 1.3kg/cm2 at zero atmospheric pressure.This item is non application specific. Please verify compatibility before purchase. May require some modification for proper installation.