Exhaust› Headers, Manifolds and Components

Keller b

4-1 Holy Header

$2,445.00

SKU: KILHH4-1-SWAIN

In Stock
In Stock
Ships by Aug 31
Free Shipping over $200
$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The Killer B Motorsport 4-1 Holy Header is an exhaust manifold designed to increase exhaust flow and maximize turbocharger potential for reduced spool time. It features an equal-length design for an aggressive exhaust note and improved performance and response across the RPM band.
Show original supplier description
The Killer B Motorsport 4-1 Holy Header is a premium exhaust manifold crafted for performance enthusiasts. This header features a 321 stainless steel construction, alloyed with titanium for superior heat resistance and longevity in high-temperature turbocharger environments. The SWAIN coating further reduces engine bay temperatures and protects against heat soak. Its equal-length design and symmetrical primary tubing geometry maintain high and consistent pulse velocities, leading to quick spool-up and improved performance throughout the entire RPM range. Key features include a cast 347 stainless steel collector designed for high-velocity merging, eliminating welds and flow disruptions. Smooth mandrel bends with the largest possible diameters are used to promote non-restrictive flow. This assembly weighs 17lbs and is compatible with both OEM EJ25 oil pans and the Killer B Motorsport Performance Aluminum Oil Pan. This product is designed for Subaru EJ models, specifically the WRX (2002-2014) and STI (2004-2021). It may not fit some Forester, Outback, and Legacy models equipped with the OEM oil cooler. The header is proudly made in the USA.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

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Specifications

BrandKeller b
Part NumberKILHH4-1-SWAIN
CategoryExhaust

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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

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