Weapon R 501-122-112 K20 Sheet Metal Race Manifold 2002-2006 RSX/Civic Si 6061

Vehicle Fitment

• 2002-2006 Acura RSX (Base, FWD, K20A2)
• 2002-2006 Acura RSX Type-S (FWD, K20A2 / K20Z1)
• 2002-2005 Honda Civic Si (EP3 Hatchback, FWD, K20A2)
• K-series engine swaps using K20A, K20A2, K20Z1, or K24A1 cylinder heads

Fitment Notes

• Designed for naturally aspirated K-series applications only. Weapon R's warranty is null and void for forced induction use - any FI installation is at the builder's own risk.
• No modifications required for direct-fit installation on compatible K20A2, K20Z1, and K24A1 applications.
• Available in multiple finish options (from $749). Confirm finish variant at time of purchase.
• Not legal for use on pollution-controlled vehicles in California. Intended for off-road or competition use only.
• Professional installation recommended. Verify throttle body and fuel rail compatibility before ordering.

Features

• High-volume sheet metal plenum design maximizes airflow and delivers significant top-end power gains over the OEM factory manifold
• CNC-machined velocity stacks and flanges for precise airflow tuning and optimal port matching
• Entire manifold carefully TIG-welded to prevent leaks and cracks under sustained high-RPM use
• Fabricated from high-grade 6061 aluminum for durability, strength, and reduced weight
• Proven 15-30 hp gains on naturally aspirated K-series applications
• Quicker throttle response and improved top-end power delivery over stock

Specifications

• Part Number: 501-122-112
• Type: Sheet Metal High Volume Race Intake Manifold
• Compatible Engine Family: Honda/Acura K-Series (K20A, K20A2, K20Z1, K24A1)
• Material: 6061 Aluminum
• Construction: CNC-Machined Velocity Stacks and Flanges, TIG Welded
• Naturally Aspirated HP Gain: 15-30 hp (typical)
• Warranty Note: Naturally aspirated use only - FI use voids warranty
• CARB Status: Not Exempt - Not Legal for Sale in California
• Fitment Type: Engine-Specific (K20 Series)

Included Components

• 1x 6061 Aluminum TIG-Welded Sheet Metal Intake Manifold
• Hardware for installation (verify fuel rail and throttle body compatibility separately)

Product Description

The Weapon R 501-122-112 is a high-volume sheet metal race intake manifold engineered for Honda and Acura K-series engines, with confirmed direct-fit applications on the 2002-2006 Acura RSX (Base and Type-S) and 2002-2005 Honda Civic Si, as well as K-series engine swaps using K20A, K20A2, K20Z1, or K24A1 cylinder heads. The enlarged plenum volume and CNC-machined velocity stacks dramatically increase top-end airflow over the restrictive OEM manifold, with documented gains of 15-30 hp on naturally aspirated setups. The entire manifold is TIG-welded from 6061 aluminum, ensuring a leak-free, crack-resistant construction under sustained high-RPM use.

This manifold is designed for naturally aspirated K-series applications only - forced induction use voids Weapon R's warranty and is not supported. No modifications are required for installation on compatible applications. This product is not CARB exempt and is not legal for use on public roads in California.