Killer B Motorsport 4-1 Holy Header

Part #: KIL HH4-1
( 9 reviews )


MSRP: $1,571.00


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Out of Stock
Orders placed today should ship by 08/10/2016



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 TR 2006, 2007WRX Limited 2006, 2007WRX 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 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 4 months 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 5 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: Sound  Boxer_WRX 1 month ago

    Will this header keep the amazing rumble sound ?

    • A: This is an equal length header. It will not retain the Subaru rumble, but still sounds great.

      Josh P. 1 month ago

  • AnswerQ: Tune  SubieLover04 2 months ago

    When installing these headers is a tune required? If so what would the damages be if you do not get one?

    • A: You can run the header without a tune, but you would not see any power gains without a custom tune.

      Josh P. 2 months ago

  • AnswerQ: Future rotated build  sml101402238 3 months ago

    If I decide to go with a rotated setup later on down the road is this setup upgradeable to work? Or should I consider a different setup?

    • A: You would not be able to upgrade this kit to work with a rotated setup, the uppipe is not compatible. You could fabricate/modify the existing uppipe or purchase one of the Killer B Motorsports DIY uppipe's that come with a v band flange and an uppipe. Keep in mind both routes will require welding. Please contact our customer service department if you have any other questions.

      Tyler.G 3 months ago

  • AnswerQ: 15 STI killer b   lupe_solis6546035 3 months ago

    Hello is this holy header the newest updated version like the one they sell on their website?

    • A: Yes, this is the newest version.

      Josh P. 3 months ago

  • AnswerQ: About ceramic coated version  Kaiwei Wang 3 months ago

    Hello, do you have the ceramic coated version of this Header? Because it will be great if it's come with ceramic coated, no offense but subispeed have them, but the people who work in subispeed is suck, and very bad after-sale service, if u guys can provide the ceramic coated version I will absolutely buy it form rallysportdirect!

    • A: We do not carry the ceramic coated version of the header. We are not aware of Killer B selling a version of this header that is ceramic coated.

      Tyler.G 3 months ago