Skip to main content
ASK OUR EXPERTS
1-866-464-6553

Plenum top for Ultra Lo-Ram 300-621BK

Black Finish

Part # 300-604BK

Plenum top for Ultra Lo-Ram 300-621BK

In Stock
Free Shipping - Lower 48 US States
Clearance
$146.97
was $234.00
save $87.03
Add to Wishlist
3

Emissions

This part is legal for sale and use on Uncontrolled (Non-Emissions Controlled) Vehicles.

See Emissions Details
The Holley LS1/2/6 Ultra Lo-Ram intake manifold kits are designed for GM LS Gen III and IV engines equipped with GM LS1/2/6 (cathedral port) cylinder heads. These intake manifold and rail kits will work with OE or aftermarket cylinder heads. The 300-604 is the plenum top in the 300-621BK complete kit. Offering this separately allows you to select your components individually as you build your system. The Ultra Lo-Ram intake manifolds are designed for forced induction (supercharged or turbocharged) engine applications and the 105 mm throttle body part number 112-581 or similar models. The base intake manifold is designed with a lower overall height to fit under a stock or mildly modified hood in the front-feed configuration. The 300-621 Ultra Lo-Ram plenum entry was configured to provide a very low profile modular intake manifold suitable for turbocharged or centrifugally supercharged engines. The fuel rail kits come with two sets of brackets. A set for long (usually standard length) fuel injectors and a set for short (such as Pico, or LS7) fuel injectors.

Features:

  • Individual plenum top for 300-621BK allows you to select your components individually as you build your intake system
  • Designed for GM LS Gen III and IV engines equipped with GM LS1/2/6 (cathedral port) cylinder heads
  • Designed for forced induction (supercharged or turbocharged) engine applications with peak power at 7000-8000 rpm depending on the application
  • Modular design allowing the use of the included front plenum entry
  • Intake design facilitates custom inlet duct and throttle body placement
  • Low height to fit under a stock or mildly modified hood.
  • Front entry plenum flange allows design & fabrication of special throttle body adapters or inlet ducts for custom installations
  • Clears 1998-2002 (4th Gen) Camaro/Firebird and 1997-2004 (C5) Corvette cowls and hoods without modification
  • High volume fuel rails and mounting hardware included with ¾”-16 o-ring ports (8 AN)

About Holley EFI

Find standalone EFI for LS, Coyote, Hemi and more at Holley.com. From engine swapping to managing up to 4000 horsepower, we have a solution for every project!

Brand Holley EFI
Clearance CategoryAir and Fuel Delivery
ColorBlack
ConstructionCast
Discount Percentage5-25%
Emission Code3
EngineGM LS1/LS2/LS6
FinishBlack
Fuel System TypeEFI
Manifold TypeUltra Lo-Ram
Product TypeIntake Manifold Top
Recommended UseForced Induction
Sale CategoryAir and Fuel Delivery
WarrantyLimited 90 Day
UPC090127079461
Part Number300-604BK
3

This part is legal for sale and use on Uncontrolled (Non-Emissions Controlled) Vehicles.


The following vehicles are considered Uncontrolled (Non-Emissions Controlled) Vehicles:

  • 1965 and older U.S. manufactured California Certified vehicles
  • 1967 and older U.S. manufactured Federally Certified vehicles
  • 1967 and older Foreign manufactured vehicle


WARNING: It is against the law to install this part on an Emissions Controlled Vehicle


The following vehicles are considered Emissions Controlled Vehicles:

  • 1966 and newer U.S. manufactured California Certified vehicles
  • 1968 and newer U.S. manufactured Federally Certified vehicles
  • 1968 and newer Foreign manufactured vehicle
Limited 90 Day: See Details

*Free Shipping & Handling only offered to the contiguous US on orders over $149, excludes clearance parts and oversized packages.

Some parts are not legal for use in California or other states with similar regulations.