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Polished stainless steel 4-1 exhaust manifold with CNC flange and metal gasket

Dyno Racing

Dyno Racing Stainless Steel Manifold Header 2002-2006 Civic Si EP3 Acura RSX DC5 2.0 K20 Exhaust System

SKU CH-FJ04-CQDMK

T-304 stainless steel 4-1 header for 2002-2006 Civic Si and RSX K20 engines, TIG welded with CNC flange and metal gasket, adds 10-15 hp

  • Exhaust TypePipes & Tips
  • T-304 stainless steel construction resists corrosion for long service life
  • TIG welded CNC machined flange ensures precise fit and leak free sealing
  • Metal gasket included simplifies installation with no extra parts needed
  • 4-1 racing design improves exhaust scavenging to free up 10 to 15 hp and torque
  • Direct fit for 2002 to 2006 Civic Si EP3 and Acura RSX DC5 2.0 K20 engines

Application Scope

This stainless-steel exhaust manifold header fits the Acura RSX DC5 and the Honda Civic Si SiR when equipped with the 2.0L K20 engine. The 4-1 JDM racing design uses T-304 stainless steel with TIG welded CNC machine flanges and includes a metal gasket.

Who It Suits

Builders seeking a direct bolt-on header for off-road racing use on the specified K20 platform will benefit from the claimed 10 to 15 Hp/Tq gain. Buyers who need a street-legal emissions compliant manifold or a header for a different engine variant should look elsewhere.

Deciding Specification

The single specification that decides fitment is the 2.0L K20 engine code; the header is listed for that engine only and is not confirmed for any other displacement or engine family.

Highlights

  • T-304 stainless steel construction resists corrosion for long service life
  • TIG welded CNC machined flange ensures precise fit and leak free sealing
  • Metal gasket included simplifies installation with no extra parts needed
  • 4-1 racing design improves exhaust scavenging to free up 10 to 15 hp and torque
  • Direct fit for 2002 to 2006 Civic Si EP3 and Acura RSX DC5 2.0 K20 engines

Specifications

Exhaust TypePipes & Tips

Questions about this item

Will the T-304 stainless steel header need any replacement parts or maintenance down the line?

The header is built from T-304 stainless steel with TIG-welded CNC flanges, which resists corrosion and cracking under normal street or track use; the included metal gasket is the only wear item and should be replaced if the header is ever removed.

What is the first limit you hit when running this 4-1 header hard for extended periods?

The 4-1 design is tuned for the 2.0L K20 engine to reduce backpressure, so the practical limit under sustained load is the engine's own airflow capacity rather than the header itself.

How much hotter or louder does the engine bay get with this header during all-day driving?

The thinner-wall T-304 tubing and 4-1 merge raise exhaust gas velocity, which increases under-hood heat and produces a noticeably louder, more aggressive exhaust note compared with the factory manifold.

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