Holley EFI 300-621-120K LS1/LS2/LS6 Ultra Lo-Ram EFI Intake Manifold Kit with 102mm Throttle Body & 120lb Injectors

The Holley EFI 300-621-120K is a complete Ultra Lo-Ram EFI intake manifold kit for GM LS Gen III and IV engines equipped with LS1/LS2/LS6 cathedral port cylinder heads. This ready-to-run bundle pairs the proven 300-621 Ultra Lo-Ram manifold with a 102mm throttle body and high-flow 120 lb/hr fuel injectors, giving high-horsepower forced induction builds everything needed in a single package.

Forced Induction, Low-Profile Design:

The Ultra Lo-Ram's front-feed plenum entry delivers an extremely low overall height, engineered specifically for turbocharged and centrifugally supercharged applications. The manifold's short runner design pushes peak power into the upper rpm range—typically 7,000–8,000 rpm—where boost-fed engines perform best. The low-profile construction clears 4th Gen Camaro and C5 Corvette cowls and hoods without modification, and fits under a stock or mildly modified hood.

Key Features:

• Designed for GM LS Gen III & IV engines with LS1/LS2/LS6 (cathedral port) cylinder heads
• Compatible with OE or aftermarket cylinder heads
• Optimized for forced induction (turbo or centrifugal supercharger) applications
• Front-feed plenum entry for very low profile hood clearance
• Modular design facilitates custom inlet duct and throttle body placement
• Cast aluminum construction with natural satin finish
• Includes 102mm throttle body for maximum airflow
• Includes high-flow 120 lb/hr fuel injectors for high-horsepower builds
• High-volume fuel rails with 3/4 in.-16 O-ring ports (8 AN) included
• Fuel rail kit includes two sets of brackets — one for long (standard length) injectors and one for short (Pico/LS7) injectors
• Plenum top mounting flange height: 5.17 in.
• Front-feed plenum configuration height with throttle body adapter: 6.86 in.
• Clears 4th Gen Camaro and C5 Corvette cowls and hoods without modification
• Legal for sale and use on uncontrolled (non-emissions controlled) vehicles

This complete kit eliminates the guesswork of sourcing matched components for a high-output LS forced induction build, delivering the intake manifold, throttle body, and injectors together in a natural finish.