KILLER B 4-1 EQUAL LENGTH HOLY HEADER - 2 BOLT - 02-14 WRX, 04-21 STI, 05-09 LGT, 04-13 FXT
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.
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 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 without exceeding the temperature range like you can with 304 stainless.
Made in the USA and Killer B Quality!
Every Header setup is inspected, assembled and pressure tested before it ships to assure a leak free setup!
- This is the 2-Bolt Uppipe flange not V-Band.
- SwainTech coating is NOT included.
- Killer B Motorsport does NOT warranty wrapped headers.
- Works with OEM EJ25 #11109AA151 Oil Pans, and Killer B Motorsport Performance Aluminum Oil Pan.
- Designed to work with OEM location turbo.
- Some vehicle such as 2006-2007 WRX / 2004-2013 Forester XT may require converting to the 2002-2005 WRX type oil cooler setup or removal of the oil cooler setup due to contact issues that maybe had during installation.
- Will NOT fit FA20DIT WRX engines.
2004-2020 Subaru STI & Type-RA
2002-2014 Subaru WRX (Requires triangle oil pan #11109AA151)
2005-2009 Subaru Legacy GT & Spec B
2004-2013 Subaru Forester XT
2005-2009 Subaru Outback XT
2005-2006 Saab 9-2X Aero
All USDM & JDM EJ-Series Turbo Engines (EJ205 / EJ207 / EJ22T / EJ255 / EJ257 / EJ257B / EJ20X / EJ20Y)