Terminator Stealth EFI 2x4 Upgrade Components are a fast, easy way to step up your entire system using the throttle body you already have. Ideal for converting a 2x4 supercharged combination to EFI, they provide the classic look of a Holley 4150 carburetor but with all the benefits of modern fuel-injection technology. Just take your pick from three throttle body finishes (hard-core grey, classic gold, and polished), install the slave throttle body and plug-and-play main harness, and have a certified Holley EFI tuner/installer tune it with a laptop.