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Polished stainless steel 4-2-1 exhaust manifold header with three O2 sensor ports and blanking plugs

Dyno Racing

Dyno Racing Stainless Steel Manifold Header 4-2-1 1.75" 2.50" 2002-2006

SKU CH-K342-5P49F

Stainless steel 4-2-1 header with 1.75" inlet, 2.50" outlet and three O2 sensor ports fits 2002-2006 Civic Si and RSX Base

  • Exhaust TypePipes & Tips
  • Fits Honda Civic Si and Acura RSX Base 2002-2006
  • 4-2-1 piping design improves exhaust flow
  • 75" inlet and 2.50" outlet for performance
  • High-quality stainless steel with CNC flanges and TIG/MIG welds
  • Includes three O2 sensor ports with blanking plugs

Application Fit

This stainless steel manifold header is built for the Honda Civic Si and Acura RSX Base produced between 2002 and 2006. It replaces the factory exhaust manifold with a 4-2-1 piping layout that uses a 1.75 inch inlet and a 2.50 inch outlet. The kit includes three O2 sensor bungs and blanking plugs for models that do not require all three sensors.

Who It Suits

Enthusiasts seeking a direct-fit header for the listed K-series engines will appreciate the CNC-machined flanges and TIG and MIG welded construction. Builders working on other Honda or Acura models, different model years, or engines that require a different port configuration should look elsewhere. The product ships without installation instructions, so professional fitting is strongly advised.

Sustained Load Behaviour

The polished stainless steel construction resists corrosion and heat cycling during extended high-rpm operation. The 4-2-1 design promotes scavenging across a broad rev range rather than a narrow peak, helping maintain consistent exhaust flow under prolonged track or spirited driving conditions. All welds and flanges are engineered to withstand repeated thermal expansion without cracking.

Highlights

  • Fits Honda Civic Si and Acura RSX Base 2002-2006
  • 4-2-1 piping design improves exhaust flow
  • 75" inlet and 2.50" outlet for performance
  • High-quality stainless steel with CNC flanges and TIG/MIG welds
  • Includes three O2 sensor ports with blanking plugs

Specifications

Exhaust TypePipes & Tips

Questions about this item

Does this manifold header bolt to the factory exhaust flange on my 2002-2006 Civic Si or RSX Base without an adapter?

The header uses CNC-machined flanges designed for the K-series engine found in the 2002-2006 Honda Civic Si and Acura RSX Base, matching the OE exhaust port spacing and bolt pattern.

Will the three O2 sensor bungs on this header align with the wiring harness and ECU calibration of my stock 2002-2006 RSX Base?

The header provides three O2 sensor ports with blanking plugs; the port locations follow the factory layout so the original sensors and wiring reach without extension, and unused ports can be sealed with the supplied plugs.

After fitting the header, how can I confirm the 1.75-inch primaries and 2.50-inch collector are flowing correctly?

Start the engine and check for exhaust leaks at the flange and O2 bungs; a smooth idle, no check-engine light, and normal fuel trims on a scan tool indicate the 4-2-1 design is sealing and flowing as intended.

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