FAST LSXRT 102mm Truck Intake Manifold (Cathedral Port Heads)

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  • Regular price $1,049.95

Injection Molded Polymer Intake
Cathedral-Port Head Equipped Applications

Designed specifically for GM 4.8/5.3/6.0L cathedral port cylinder head-equipped truck engines and cathedral port LS1, -2, -6 applications where hood clearance is not a concern, the FAST™ LSXRT™102mm Intake Manifold follows the path chartered by the original FAST ™ LSX™ Gen III Intake by featuring a modular design that allows for easy porting and disassembly and a runner design that yields an incredible 25 peak horsepower gain over the stock intake, on a stock 6.0L engine with a Big Mouth 102mm Throttle Body™. Extensive testing led to a runner design that is longer and less restrictive and gives the user the ability to remove individual runners from the manifold for modification.

The LSXRT™ is constructed from a proprietary precision injection molded polymer which offers many benefits, including lighter weight, greater strength and lower heat soak propensity. While it features a 102mm air inlet that was designed for the FAST™ Big Mouth 102mm Throttle Body™, it can also be used with OEM electronic 78/90mm or aftermarket 90/92mm throttle bodies (three-bolt electronic throttle bodies require an adapter). Other features include integrated nitrous bungs and a precise bolt-on fit that permits the use of factory accessories and OEM fuel/emission connections without adjustments or clearance issues.

  • 25 HP gain when used w/ 102mm Big Mouth Throttle Body™ on a stock 6.0L truck engine

  • Constructed from proprietary precision injection molded polymer;  Lighter than aluminum w/ lower heat soak propensity & greater strength over stock molded intake

  • Innovative multi-layer design w/ removable runners for quick & easy disassembly & porting

  • Integrated nitrous bungs; plug-and-play w/ ZEX™ LSX™ Direct Port Nitrous System

  • Patented Design - U.S. Patent No 8,567,366



OEM 99-07 Round fuel rails

Important Notes:

  • Works with all GM LS-based engine (4.8/5.3/6.0) equipped Truck/SUV's fuel rails produced from 2007-2014 (square metal-style)
  • Requires permanent modification to fuel rails. Making them unsuitable for use with OEM LS truck intakes after modifications are complete.
  • Works with OEM Truck/SUV injectors* only. Includes brackets for use with Flex Fuel or Non-Flex Fuel style injectors.

OEM 07-14 Square fuel rails

Important Notes:

    • For use w/ all GM LS-based engine (4.8/5.3/6.0) equipped Truck/SUV's fuel rails produced from 1999-20071 (round plastic-style)
    • Requires permanent modification to fuel rails. Making them unsuitable for use with OEM LS truck intakes after modifications are complete.
    • For use w/ OEM Truck/SUV injectors2 only. Includes brackets for use w/ Flex Fuel or Non-Flex Fuel style injectors.

Billet Fuel Rail Kit

The FAST™ High Flow Billet Fuel Rails feature a larger internal diameter that dampens the pulses and provides increased fuel volume, ensuring that your injectors never run dry. In addition, they yield better fuel distribution and ultimately greater horsepower. Featuring high strength billet, lightweight, red anodized aluminum construction, FAST™ LS1 fuel rails deliver performance in addition to a show car quality appearance.

  • For use w/ OEM Truck/SUV injectors* / But can be configured for LS2-style injectors

  • Includes Red Anodized Fuel Rails & Black Anodized #8 Fittings w/ “Super Seal” O-Rings



1. Chevy Trailblazer SS requires some cowl modifications.
2. FAST™ throttle body requires GM purge solenoid #12581282 (Not sold by FAST™)
3. Drive-by-wire applications must re-use OEM throttle body or purchase aftermarket drive-by-wire throttle body.
4. Fuel line adaptor(s) required to connect to OEM fuel line(s).