K-Tuned 409 Series Header - 06-11 Civic Si

K-Tuned 409 Series Header - 06-11 Civic Si

The K-Tuned 8th gen / 06-11 Civic Si header was specifically designed to optimize the performance and power output of the K20Z3 engine that is found in all 2 and 4 door SI models. The header was developed using a proven 4-2-1 Tri-Y design that delivers power gains almost everywhere in the power band, not just the higher rpm range. Additional performance is accomplished by using large diameter piping to speed up the flow of exiting exhaust gases. K-Tuned also uses stepped piping and smooth transitions that minimize restriction. Fitment past the subframe and sway bar is perfect with extra clearance available for engine movement.

This header starts with 44mm primaries that smoothly step into 50mm secondaries and finish with a 64mm or 2.5” exit. Like all K-Tuned headers, it is assembled using mandrel bent, 409 series steel tubing and is fully tig welded. We also use a slightly thicker gauge tubing that allows for better weld penetration and additional strength. The CNC cut 3/8" thick flanges are also double welded and then ported for optimum flow at entry and exit. This header directly replaces the OEM 2 piece design and eliminates the catalytic converter so we included a short 2.5" test-pipe with defouler for the secondary O2 sensor.


After evaluating the price driven exhaust parts market and seeing some of K-Tuned products copied using very low quality, thin gauge Asian mystery material, K-Tuned 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. The 409 Series Headers are exactly like K-Tuned stainless steel headers, they only changed the material to save 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.

Vehicle Application:
Direct bolt-on for all 06-11 Civic Si models (sedan and coupe).


  • Fits Civic Si w/K20Z3 engine
  • 4-2-1 Tri-Y Design
  • 409 series steel
  • CNC cut 3/8" thick SS Flanges
  • 2.5" Outlet

This is a Race Only product that is to be used solely for competition. It cannot be used on vehicles that are operated on public streets, roads or highways. Its use is limited to closed-course and open-course racing that is formally sanctioned by a recognized racing organization. Any other use, including recreational off-road use, could be in violation of local, state and federal laws.

K-Tuned 409 Series Header - 06-11 Civic Si

Regular price Sale $332.99
Ships: Pre-order
This is an estimated ship date once your order is placed from JHPUSA. Ship dates do not include weekends and holidays.
California Residents Warning:
Cancer & Reproductive Harm
Welcome Newcomer