Koyo introduces the All Aluminum Race radiator for the 08-10 Subaru Impreza WRX w/ 5MT & 08-10 Subaru Impreza STI w/ 6MT! The Subaru STI Radiator is the very first application to feature Koyo’s brand new “Hyper V” racing core. Koyo engineers have determined that 08-10 Subaru STI and 08-10 Subaru WRX have different cooling needs, therefore Koyo offers a different radiator for each with different part numbers. Koyo Part# VH13093 was engineered specifically for the 08-10 Subaru STI and Koyo Part# V13091 was engineered specifically for the 08-10 Subaru WRX.