Billet Aluminum Oil Filler Caps, Billet Aluminum Spark Plug Wire Covers, Intake Manifold Covers, Aluminum Fuse Box Covers, etc. Injen Technology develops accessories to compliment the engine bay of some of todays most popular vehicles. Injen utilizes only the finest materials to produce durable and show-quality parts for the enthusiast looking to enhance the appearance of the engine bay. All billet parts are CNC machined from 6063 T-6 aluminum alloy. The sheet metal parts are stamped in punch presses or CNC fabricator with auto-index tooling. In todays hi-tech world, Injen Technology produces only precision and quality parts guaranteed to fit every time.