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Killer B Motorsport 4-1 Holy Header Exhaust Manifold 2 Bolt 2002-2014 WRX / 2004-2021 STI

SKU HH-2BOLT
Original price $1,539.00 - Original price $1,989.00
Original price
$1,539.00
$1,539.00 - $1,989.00
Current price $1,539.00
Pay Over Time
Only 3 Left In Stock! Usually Ships within 1-2 Business Days
4 In Stock, Usually Ships within 1-2 Business Days

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.

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 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 (and keep the warranty) 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!

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.

Customer Reviews

Based on 7 reviews
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T
Titus Jones
Easy to see why they call it the holy header

This part is solid well built, with great fit and finish, I can’t wait to see how it pairs with my new Dom 1.5 in my 05 forester xt build!

Titus,

Thank you for the awesome 5 Star Review! We are delighted that you are pleased with your purchase. We are here for you anytime—enjoy the upgrades!

Regards,

J
J.
Amazing headers

Headers look slick nice welds

J.R.,

Thank you for your positive feedback and 5 Star Review of the Killer B Motorsport 4-1 Holy Header Exhaust Manifold! We are glad to hear that you are impressed with the look and welds of the headers. Killer B strives to provide high-quality products for customers and the Subimods Team is happy to know that we met your expectations. Thank you for choosing Subimods and we hope you continue to enjoy your Holy Headers! Have a great day!

Regards,

k
k.s.
02 sensor

is there an o2 sensor in the header?

Hello,

Yes there is!

Regards,

M
Mark Williams
Best header ever

Fit perfect totally worth the money . Subimods all ways coming out on top

Mark,

Thank you for your glowing 5 Star Review! Subimods is thrilled to hear that you consider the Killer B Motorsport 4-1 Holy Header Exhaust Manifold with 2 Bolt fitment to be the best header ever. It is great to know that it fit perfectly and was worth the investment. At Subimods we strive to provide quality products, and your positive feedback encourages us to continue delivering top-notch solutions. If you have any more comments or if there's anything else we can assist you with, please feel free to reach out. Thank you for choosing Killer B Motorsport and Subimods!

Regards,

A
Andrew Protacio
Great quality!

Very high quality product, however, someone took the sticker that was supposed to come with it. Manufacturer decals are a part of that unboxing experience, but that was robbed from me! Anyways, great, solid piece of equipment.

Andrew,

Thank you for the 5 Star Review! The Killer B Motorsports 4-1 Holy Header Exhaust Manifold is one of the best designed and manufactured header on the market! Killer B Motorsports truly knows what they are doing to achieve the best performance from their products. I am sorry your unboxing experience was spoiled with no sticker! Definitely contact Killer B I guarantee they will send you one!

Regards,

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