This fabricated aluminum plenum top mounts to Holley's existing Hi-Ram manifold bases and moves the throttle body to the side of the intake — a layout that resembles older Ford EFI manifolds and frees up room in tight engine bays for boosted or custom builds.
Specifications:
- Construction: Fabricated, 4mm-thick aluminum
- Finish: Silver
- Inlet Size: 95mm
- Throttle Body Pattern: LS-style
- Mounts To: Existing Holley Hi-Ram manifold bases
- Warranty: Manufacturer's Limited 90 Day Warranty
- Part Number: 300-284
Also offered in 105mm sizing and in an 86-95 Ford 5.0-style throttle body pattern; see the product images for full dimensions.
FAQ
What manifold does this plenum top fit?
It mounts directly to Holley's existing Hi-Ram manifold bases.
Why choose a side-mount plenum top?
Side-mounting the throttle body frees up room in tight engine bays, making it easier to fabricate boosted setups or achieve a different look.
What throttle body pattern does this version use?
This 95mm version uses an LS-style throttle body pattern; a Ford 5.0-style pattern is also available.
What material is this plenum top made from?
It's fabricated from 4mm-thick aluminum with a silver finish.

