Click Here to see YimiSport full review of the

Killer B Motorsport Holy Header

Killer B MotorsportLLC


The Killer B Motorsport Holy Header was developed using state of the art CAD software & simulations to determine optimal design to increase power as much as possible throughout the rev 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/boost response and the ability to hold more power higher into the revs.


Features include:



· Cast Collector. The collector is thick walled cast 347 (321) stainless. The casting removes several welds, each weld removed is one less flow disruption (reduced turbulence). The casting has features milled into it that assure the primary tubes fit VERY concentric every time. Using a casting allows the collector to be designed as a true high velocity merge vs tubing that can only be formed a little bit, and not ideally. The casting is thicker/stronger than formed tube and also holds heat better.


· 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, we 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 our 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 secondaries 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 our 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.


· Works with OEM EJ25 Oil Pans, and Killer B Motorsport Performance Aluminum Oil Pan!


· Fits All WRX & STi EJ Series Engines. Designed to work with OEM location turbo. See below for ‘DIY rotated setup.


· Available with External WasteGate Option or 2 Bolt Manifold Only


· Made in the USA!

Killer B Motorsport WRX / STi HOLY HEADER - Patent Pending


About Us

Contact Us


Custom Search
Killer B Motorsport Design and Manufactures Aftermarket Performance Subaru Impreze WRX and STI parts

NEW Developments

Technical Tidbits

Killer B Motorsport Header Review by YimiSport

+40wtq gains

+27whp peak gains

· More power EVERYWHERE!

What can be expected from Killer B Holy Headers?


·  Improved throttle and Boost Response


·  Customers report +25wtq and +25whp on average


·  More Consistent EGTs across all cylinders


·  More Power Higher into the Rev range


·  Improved Fuel Efficiency


·  Perfect fit! (some WRX models may requite OEM Oil Cooler to be rotated)


External WasteGate

· Provides More Precise Metering of Boost for Faster Spool and Responsiveness

· Improved Power Due to reduced IWG/Turbine Turbulence

· Up-Pipe ‘Stub’ Machined from Solid 321 Stainless Bar for a Perfect Fit and Thick Wall Reliability

· V-Band Connections (no gaskets needed)

· Includes Vent-to-Atmosphere Dump Tube

· Designed for Maximum Flow using a 38mm WasteGate

EXTRAS / SPARES: V-Band Clamps, Gaskets, Studs and more...

External Waste Gate



· Works with any 2-Bolt Up-Pipe, including rotated

· Two-Bolt Reduced cost!

· Up-Pipe not included

Holy Header Equal Length 4-into-1 with Up-Pipe
EWG Holy Header Equal Length 4-into-1 with Up-Pipe
2 Bolt Holy Header Equal Length 4-into-1
Extras / Spares

Contact us for availability

(888) 687-1117

Contact us for availability

(888) 687-1117

Contact us for availability

(888) 687-1117