Mid-Rise Plenum Base Adapter Kit Black Mid-Rise Plenum Base Adapter Kit GM LS1/LS2/LS6 Black HolleyFor use with Ls Dual Plane Mid Rise intake manifold base to adapt to modular tops. The Modular Mid Rise intake utilizes the popular Holley LS1 LS2 LS6 cathedral port Mid Rise 2 x 4 intake manifold along with a purpose built plenum base adapter and a Holley 92MM EFI plenum top which converts it into a Mid Rise EFI intake manifold. With a max overall height of only 10. 44 inch, the Mid Rise manifold is an excellent choice for street and performance