The Qualifier EFI Manifold System for 5.0L and 351W Fords is an ideal performance upgrade for your Mustang or other vehicle with one of these engines. This manifold is suitable for high performance street use, bracket racing, nitrous, or supercharged applications. The 5.0L System is sold as a complete kit with both the lower manifold and upper plenum in one package. However, if you have a 351W engine, you need to buy the 351W manifold and the upper plenum separately. Note that our Upper Plenum will bolt to an Edelbrock #3821 or #7126 manifold. If a customer already has an Edelbrock setup it is an easy and economical swap to bolt on one of our polished upper plenum units.