4-2-1 K-Swap Header
409 Series Stainless Steel

Your Price: USD $284.99
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Part Number:KBH-421-409

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Customer Notice: I understand this product is sold for RACE use only and is not legal for use in highway or street vehicles. K-Tuned makes no representation or claims that this product complies with any emissions standards
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  • 92-95 Civic EG K-Swapped
  • 96-00 Civic EK K-Swapped
  • 94-01 Integra DC2 K-Swapped
  • 88-91 Civic EF K-Swapped with slight notching of subframe


* 409  Steel

* 4-2-1 Design

* CNC Cut Flanges

* 2.5" Outlet Flange


*Hasport EKK1 and EKK2 mounts will work with this header

K-Tuned 4-2-1 K Swap Header

This header is capable of making very good power on relatively stock or mild engine setups.  The main focus while designing our K-Tuned Swap Header was to blend excellent fitment, high quality construction and keep the price reasonable.  We have upsized the primary piping slightly and improved the quality of all transitions to improve exhaust flow.  The primary to secondary transition now uses an expanded secondary pipe at the joint to eliminate any restriction.  The secondary pipes have also been changed a little and now merge together better at the collector.  The header is constructed with 409 steel with 3/8' thick flanges that are double welded and then ported for optimum flow.  The piping is extra thick for added strength and to allow better weld penetration.  These strength features add longevity and make a header that will be able to take the abuse of a firmly mounted K-swap engine.  The strong interlocking flex-pipe can handle a lot of heat and has a 2.5' ID (Inside diameter).  It flows very well and absorbs engine movement.  Like our other headers, they are designed to fit most K-swap chassis perfectly.  The header does not interfere with shifter mounting kits and is well centered in the exhaust tunnel.  The 3-bolt exit flange prevents leaks and allows for installation to the existing exhaust piping with minimal modification.  Please note that all of our headers will require some exhaust welding for installation.


After evaluating the price driven exhaust parts market and seeing some of our products copied using very low quality, thin gauge Asian mystery material, we decided it was time to make a move. K-Tuned 409 Series Headers are made with raw 409 series steel which will offer customers a cost savings with no sacrifice to performance and fitment. We wanted to maintain a high level of quality because our stainless headers have had a good reputation for several years now. Our 409 Series Headers are exactly like our stainless steel headers, we only changed the material to save our customers a few dollars. The raw steel finish can be high heat coated or painted to resist rust or left as they are to let nature have its way. These headers are intended for use on simpler street cars that are more about function rather than looks and to be honest some hoods are only opened when needed.

The exhaust parts market is filled with a lot of knock-offs, misinformation and deception. We aren't going to bring company names into this conversation, but some of these replica producing companies are currently selling exhaust products that are said to be X material when in fact the material is not even close to what they say it is. Not all the fault lays on the reseller because there is a lot of mystery material coming out of Asian manufacturing. What some advertise as 304 stainless has been found to actually be 200 series. Another cheat we have seen is cutting down the wall thickness of the piping to cut the cost. The problem with using a thinner gauge material is it weakens the product and can cause premature cracking. We have seen piping advertised as 16 gauge, end up measuring as 18 or even 20 in some cases.

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