If you just purchased the Koyo Radiator, you can maximize the performance with the Koyo 1.3 Bar High-Pressure Radiator Cap! These are finished in Hyper Red, and reviewers of this radiator cap have been pleased with the looks, and performance of this radiator cap. 

This Koyorad Hyper Cap withstands an increased valve pressure rating of 1.3kgf/cm2 (1.3 bar) (18.9 psi) (130 kPa) which increases the boiling point of water and relieves high-performance engines of excessive heat. These are highly recommended for use with every KoyoRad All Aluminum Radiator (when applicable). 

The KoyoRad Hyper cap is crafted in Japan from high-quality materials to ensure longevity and performance from your KoyoRad Racing Radiator.