FAST LSXR Manifold 102MM LS1/2/6 Intake Manifold Kit - Black

Cathedral Port LS Power Unleashed: 102mm Throttle Body, Removable Runners, and Nitrous Ready Design

The FAST LSXR 102mm Intake Manifold Kit 146302B-KIT is the complete bolt on solution for cathedral port LS builds demanding maximum airflow and broad power delivery. Engineered for LS1, LS2, and LS6 engines as well as the truck based LQ4, LQ9, L33, and LC9 variants, the 146302B-KIT combines an advanced polymer manifold with a FAST Big Mouth 102mm billet aluminum throttle body in a single package. The manifold's three piece modular construction features fully removable runners, allowing tuners to dial in runner length for specific RPM targets without replacing the entire manifold. With an RPM range of 1800 to 6000, the 146302B-KIT delivers usable power across the entire rev range of street driven and track prepared LS vehicles. CARB EO numbers D-279-9 and D-279-10 confirm 50 state street legality for the 146302B-KIT.

Key Features

• 102mm throttle body bore paired with the FAST Big Mouth billet aluminum throttle body (cable drive)
• Three piece modular design with fully removable runners for tunable power characteristics
• Advanced polymer construction in black resists heat soak and reduces weight versus cast aluminum
• Compatible with cathedral port heads: LS1, LS2, LS6, LQ4, LQ9, L33, LC9
• Integrated nitrous bungs for direct port nitrous system plumbing
• EGR provision retains factory emissions components where required
• IAC (Idle Air Control) and TPS (Throttle Position Sensor) included
• CARB EO D-279-9 / D-279-10 compliant, 50 state street legal
• Broad power band from 1800 to 6000 RPM for street and track use
• Requires FAST billet fuel rails or fuel injector adapter kit for OEM rails (sold separately)

Specifications

What's Included

• FAST LSXR 102mm Advanced Polymer Intake Manifold (Black)
• FAST Big Mouth 102mm Billet Aluminum Throttle Body (Cable Drive)
• IAC (Idle Air Control) Valve
• TPS (Throttle Position Sensor)
• Integrated Nitrous Bungs
• Hardware and Installation Instructions

Fitment

Not compatible with: Rectangular port heads (LS3, LS7, L92, L99). For LS7 applications, see FAST 146202B-KIT. For rectangular port heads, see FAST 146102B-KIT.

Frequently Asked Questions

1. Does the FAST 146302B-KIT work with a stock LS1 in a 1999 Camaro?
   Yes. The 146302B-KIT is a direct fit for the LS1 cathedral port head configuration found in 1997 through 2004 F body, Corvette, and GTO applications. You will need FAST billet fuel rails or a compatible injector adapter kit for the OEM fuel rail setup, and LS1/LS2 head gaskets are not included.
2. What fuel rails are required for the FAST LSXR 102mm manifold?
   The 146302B-KIT requires LS2 style billet fuel rails. FAST offers compatible billet rails separately. OEM LS1 rails can be adapted with FAST's fuel injector adapter kit. Standard OEM LS1 rails do not bolt directly to the 146302B-KIT without an adapter.
3. Can I use the 146302B-KIT on an LQ9 truck engine swap?
   Yes. The LQ9 uses cathedral port cylinder heads, making it fully compatible with the 146302B-KIT. This is one of the most popular combinations for high output LS truck swaps into cars and custom builds.
4. Is the FAST 146302B-KIT legal in California?
   Yes. CARB EO numbers D-279-9 and D-279-10 cover the LSXR manifold series, making the 146302B-KIT 50 state street legal including California.
5. What does the modular runner design on the 146302B-KIT do?
   The three piece design with removable runners allows you to change runner length for different power targets. Shorter runners favor high RPM peak power; longer runners improve low to mid RPM torque. This gives tuners flexibility without replacing the entire manifold.
6. Does the 146302B-KIT fit an LS3 or LS7?
   No. The 146302B-KIT is designed exclusively for cathedral port heads (LS1, LS2, LS6 bolt pattern). LS3 and LS7 use rectangular port heads. For LS7, FAST offers the 146202B-KIT. For LS3/L92 rectangular port, see the 146102B-KIT.
7. What size throttle body comes in the FAST 146302B-KIT?
   The kit includes a FAST Big Mouth 102mm billet aluminum throttle body with cable drive actuation. It is paired and matched to the 102mm bore of the LSXR manifold for optimal airflow continuity.
8. Do I need to retune after installing the FAST LSXR 102mm kit?
   Yes. A professional tune is strongly recommended after installing the 146302B-KIT. The significant increase in throttle body size and manifold airflow requires ECM recalibration to achieve proper air fuel ratios and optimal power delivery. The 146302B-KIT is a performance component intended for tuned applications.
9. Are gaskets included with the 146302B-KIT?
   No. Head to manifold gaskets are not included with the 146302B-KIT. Use standard LS2 style intake manifold gaskets, available from most GM performance parts suppliers.

Install Instructions

Installation of the FAST 146302B-KIT requires removal of the factory intake manifold and throttle body. Drain the coolant if the existing manifold routes coolant lines, and disconnect the IAC, TPS, MAP sensor, and fuel rails before removal. Install the provided IAC and TPS onto the 146302B-KIT throttle body prior to mounting. Torque manifold bolts to factory LS specifications (typically 8 ft lb for the first pass and 18 ft lb for final torque on most GM LS applications). Connect FAST billet fuel rails or the appropriate adapter kit to the injectors. Route throttle cable to the FAST Big Mouth throttle body. A professional tune is required after installation. Refer to the included FAST instruction sheet for complete torque specs and wiring diagrams.

California Proposition 65 Warning: This product can expose you to chemicals including lead and lead compounds, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, visit www.p65warnings.ca.gov.