Holley- 300-603BK Dual Injector LS1 Ultra Lo-Ram Manifold Base LS1/2/6


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Front-feed Dual Injector manifold and fuel rails-Black finish

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 (Original Equipment) or aftermarket cylinder heads. The 300-603(satin) & 300-603BK(black) front-feed, base-lower intake manifold provides two injectors per cylinder for hi-volume fuel demands, flexible fuel supply strategies, and dual-fuel capability. Offering this base intake manifold with fuels rails separately allows you to select your components individually as you build your induction system. Complete front-feed manifold kits are also available with dual fuel injectors, see P/N's 300-625 & 300-625BK. The front-feed, short runner, low-profile base intake manifold was conceived to package with high-boost turbocharged or supercharged induction systems with a short overall height not possible with other existing intake manifolds. The Holley Lo-Ram complete intake manifold kits and throttle body adapters available as a machined casting 300-606 & 300-606BK are configured for a 105mm throttle body, see Holley P/N 112-581 or similar models. 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. Holley Lo-Ram intake manifold kits include all the sealing o-rings, plugs, and fasteners required for the installation of the kit.


  • Designed for GM LS Gen III and IV engines equipped with GM LS1/2/6 (cathedral port) cylinder heads
  • Provides best performance for forced induction (supercharged or turbocharged) engine applications with peak power at 7000-8000 rpm, depending on the application
  • Dual-injector, separate-passage, high-volume fuel rails with mounting hardware, dual-fuel capable, 8 AN o-ring ports
  • Modular LS1 Lo-Ram design allows customization for user desired configurations
  • Low height & compact packaging allows installation in most applications often under stock hoods
  • Available with both as-cast satin and black power-coat finishes
Brand Holley EFI
Color Black
Construction Cast
Emission Code 3
Engine GM LS1/LS2/LS6
Finish Black
Fuel System Type EFI
Injector Quantity Dual
Inlet Location Front
Manifold Type Ultra Lo-Ram
Product Type Intake Manifold Base
Recommended Use Forced Induction
RPM Power Band 3500-8000 RPM
Warranty Limited 90 Day
UPC 090127079393
Part Number 300-603BK

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