HKS Fuel Rail Upgrade Kit Fuel Rail Upgrade Kit; For Top Feed Injectors for the Mitsubishi Lancer EVO 2008. HKS Fuel Rail Upgrade kits are high-performance fuel delivery units that are designed to properly supply the additional fuel needed for high boost/performance applications. HKS Fuel Rail Upgrade kits are direct bolt-on replacements of factory fuel rails, and allow for larger top-feed injectors to be added. HKS Fuel Rails are machined out of aluminum and anodized HKS? signature purple for durability and visual appeal.