The Holley EFI Vacuum Manifold kit is designed for those of you wanting a simple and clean solution for plumbing either vacuum or boost referenced sources. This manifold block features 12 1/8th NPT ports that can be plumbed with most common EFI transducers such as the Holley 554-102 0-100 psi transducer. It also features 2x -6 O-ring boss AN Ports, ensuring your manifold block has an excellent vacuum or boost reference source. Improve your engine bay organization by mounting all of your common pressure sources in one easy to access location!