Killer B Motorsport 4-1 Holy Header

Part #: KIL HH4-1
( 9 reviews )


MSRP: $1,548.68


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Brand: Killer B Motorsport
Includes Catalytic Converter: No
Installation Hardware Included: No
Manifold Design: Equal Length
Piping Coating: No
Piping Flex Joint: No
Piping Material: 321 Stainless Steel
Mfgr. Warranty: Lifetime
Return Policy:

RallySport Guarantee - 30 Days

Items that are covered under the RallySport Guarantee offer a 30 day no questions asked return policy.

RallySport Guarantee items may be returned within 30 days of the original invoice date and must include all the original parts and contents for a refund.

The RallySport Guarantee does not apply to products that have been modified, damaged, misused or abused. All returns require an RMA (Return Merchandise Authorization) Number, and freight charges are strictly non-refundable. For more information regarding our freight refund policy, please refer to our return policy page found HERE.


Subaru Impreza
WRX STI 2004, 2005, 2006, 2007WRX STI Limited 2007WRX STI Hatchback 2008, 2009, 2010, 2011, 2012, 2013, 2014WRX STI Special Edition Hatchback 2010WRX STI Limited Sedan 2011, 2012, 2013, 2014WRX STI Limited Hatchback 2011, 2012, 2013, 2014WRX STI Sedan 2011, 2012, 2013, 2014WRX 2002, 2003, 2004, 2005, 2006, 2007WRX TR 2006, 2007WRX Limited 2006, 2007WRX Sedan 2008, 2009, 2010, 2011, 2012, 2013, 2014WRX Hatchback 2008, 2009, 2010, 2011, 2012, 2013, 2014WRX Premium Sedan 2010, 2011, 2012, 2013, 2014WRX Premium Hatchback 2010, 2011, 2012, 2013, 2014WRX Limited Sedan 2010, 2011, 2012, 2013, 2014WRX Limited Hatchback 2010, 2011, 2012, 2013, 20142.5 GT Sedan 2009, 20102.5 GT Hatchback 2009, 2010
Subaru Legacy
GT Limited 2005, 2007, 2008, 2009GT 2005, 2006GT spec.B 2006, 2007, 2008, 2009
Subaru Forester
XT 2004, 2005, 2009XT Premium 2005, 2010, 2011, 2012, 2013XT Limited 2006, 2007, 2008, 2009, 2010Sports 2.5 XT 2008XT Touring 2011, 2012, 2013
Subaru Outback
XT 2005, 2006XT Limited 2005, 2007, 2008, 2009
Subaru WRX STI
Base 2015, 2016Limited 2015, 2016Launch Edition 2015
Saab 9-2X
Aero 2005, 2006

The Killer B Motorsport Holy Header was developed using state of the art CAD software & simulations to determine optimal design to increase power in the mid to high RPM range. Short as possible primaries with a single secondary significantly decrease header volume allowing exhaust gas pressure to build quickly. Symmetrical 4-1 design maintains high and consistent exhaust velocity as RPMs rise. You can expect faster spool up time compared to long primary/double secondary designs. A difference you will immediately notice in throttle response and the ability to hold more power higher into the revs.

Features include:
· Short Equal Length Primaries. The shortest possible length primaries you can have on an Equal Length header. Short means less header volume and quick spool up.
· Symmetrical Primary Design. All primaries have a similar tube length AND bend geometry. This keeps the pulse velocities high and consistent compared to equal length headers with different (non-symmetrical) primary tubing geometry.
· Smooth Mandrel Bends. All of the bends utilize a mandrel for smooth non-restrictive flow. Not only that, they use the largest bends possible at every location. It would be cheaper to use 2” bends everywhere, like others do, but that’s not going to give the best performance.
· Thick Walled 321 Stainless Steel Construction for Long Life. 321 is alloyed with titanium, costs more, a lot more, but it’s the ideal material for high temperature turbocharged applications. Would 304 stainless work, yes, but the temperatures on turbocharged cars can exceed the limits of 304 stainless enough to make them brittle and crack. 321 stainless steel has higher strength and toughness at elevated temperatures. It was developed by the aircraft industry specifically to address 304 stainless manifolds that were cracking. Killer B Motorsport is the only company that manufactures full 321 headers.
· High Heat Retention. 321 stainless steel conducts less heat than 304 stainless steel. The short primaries and properly sized secondary’s also pull less heat from the exhaust gasses increasing turbine efficiency. Large tubing headers expose the exhaust gasses to more surface area transmitting more heat and reducing exhaust energy. You can also ceramic coat or wrap the headers (and keep the warranty) without exceeding the temperature range like you can with 304 stainless.
· V-Band Up-Pipe Connection. Why V-Band? Fast, easy, no gasket, no leaks, perfectly concentric alignment of tubes for no disruption of flow, what’s not to like!
· Up-Pipe included. Of course it comes with an Up-Pipe! This header was designed as a complete system. Using other up-pipes would only compromise performance, and nobody wants that.
· Weighs only 17 pounds (vs. OEM weighs 25 pounds)
· Works with OEM EJ25 Oil Pans, and Killer B Motorsport Performance Aluminum Oil Pan!
· Made in the USA and Killer B quality!

May require slight modifications to the stock oil cooler for 06-07 WRX and Forester XT models. Some models may require modification to the stock fan shroud.




gstoker35460 20 days ago
Horsepower and torque gains on my 2012 wrx exceeded expectations of me and my tuner. HP went from 338 to 378 and TQ went from 378 to 405!

Superb product
C. Borders 2 months ago
I bought this header along with Killer B's gtx35r turbo kit and and I am very amazed with their quality of materials and performance. There is no other company I would use besides Killer B. I lost the subie rumble but prefer better performance. The 321 stainless steel is above and beyond what other companies put out on the market and if you do a ceramic coating you'll be very impressed. Big shout out to Chris from Killer B and RSD for customer support.

Heichel84 1 year ago
I have a 2015 sti with 4k miles thought I could use the original studs. Double nut method or applying heat would not get them out of the old up pipe so best to get new studs. Definitely worth the money though

Heichel84 1 year ago
I have a 2015 sti with 4k miles thought I could use the original studs. Double nut method or applying heat would not get them out of the old up pipe so best to get new studs. Definitely worth the money though

An excellent addition, even as a daily drive
Demonik 1 year ago
Got this two months back. An excellent addition to the car. The torque and throttle response is amazing. My car is a stage 2 with a Milltek turbo back and the car sounds amazing. If you would like to hear it, the clip is below I am giving it 4 stars because the Greddy Oil Sandwich Adapter GRE 12002801, does not clear the headers. So I had to remove it and I am running without a oil temperature reading at the moment. :(


  • AnswerQ: Up Pipe  Kaiwei Wang 2 days ago

    I have a 15 sti, do I need to buy another Up pipe for this header? Do I need to change bigger fuel injector or fuel pump for it? Do I need to change turbo for it?

    • A: This header setup is designed as a direct replacement and includes the uppipe. This does not require a different turbo and injectors or fuel pump would only be a requirement depending on how aggressive of a tune you are going with.

      Nick S. 2 days ago

  • AnswerQ: 2006 Subaru sti  jsanchez26 4 days ago

    Will this Headers work with Tomei exhaust on 2006 Subaru sti

    • A: As long as you are running a traditional mount turbocharger this will work with the Tomei turboback.

      Nick S. 4 days ago

  • AnswerQ: Killer B wholy header uppipe  bootsak4733656 4 months ago

    Will this fit an 02 wrx without a sti or 2.5 oil pan? Stock 2.0 oil pan?

    • A: This header will not fit with a stock 2.0L oil pan, and you will need to change to a 2.5L pan. Please keep in mind that changing to a 2.5L pan also requires a 2.5L oil pick up.

      Zach G. 4 months ago

  • AnswerQ: Ceramic coated  MrFreeze 12 months ago

    Do you guys sell the ceramic coated ones here or do I have to buy directly from killer B?

    • A: We do not offer the ceramic coated Holy Headers at this time.

      Zach G. 12 months ago

  • AnswerQ: KB Up-pipe EWG seperate available  ate2aqtr92054 1 year ago

    I originally got this and its great on my15. I may be upgrading shortblock/and turbo going EWG......can I get an KB EWG coated by swaintech by itself and swap my reg kb uppipe

    • A: No, but you can send your manifold/up back to us to perform the EWG modification to it. This is the only way to do it to assure the integrity of the v-band seal.

      Chris@KillerB 1 year ago