Does the GrimmSpeed unequal length EJ header keep the Subaru rumble?

Yes. The GrimmSpeed unequal length EJ header was designed to keep the classic boxer rumble. Each bank of runners is equal length, but one bank is 1.5 times longer than the other, which preserves the uneven sound while the equal banks keep equal length performance.

Does this header require a tune?

No. GrimmSpeed lists the header as requiring no tune and safe to bolt on. In its dyno testing the same tune stayed loaded before and after the swap, so the header was the only variable. Larger turbos or other power parts carry their own tuning needs.

Will the header fit with an aftermarket oil pan?

Yes. During development GrimmSpeed formed the header around the factory STI oil pan and around popular aftermarket pans, including those from IAG and Killer B Motorsports. Some older WRX, Forester XT and Baja fitments need the STI pan and pickup first.

Is an up-pipe included with the header?

No. The box contains the header with gaskets and installation hardware only. GrimmSpeed sells a package that pairs this header with its black ceramic coated 2-Bolt EJ25 Up-Pipe, and that up-pipe is also sold separately in raw stainless or black.

Will the header slow spool on a stock turbo STI?

Slightly. On a 2010 STI with the factory turbo, GrimmSpeed recorded some loss of spool against the stock manifold, with about 1.6 psi less average boost, but gains of up to 10.3 hp and 23.1 lb-ft. The power curve shifts toward higher rpm.

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Description

GrimmSpeed Unequal Length EJ Header for GD / GR / GV / VA Subaru STI and GD / GR / GV WRX

The GrimmSpeed unequal length EJ header is for the owner who wants the classic boxer rumble kept and the factory manifold’s choke at high rpm gone. Rather than giving each cylinder its own length, GrimmSpeed made each bank of runners equal, with one bank 1.5 times longer than the other, joined by a low-angle cast 304 stainless 4-into-1 collector. The 2004-2021 STI and 2008-2014 WRX are direct fits. Owners indifferent to the sound may prefer an equal length design.

Development and Testing

GrimmSpeed scanned the underside of several EJ setups with a FARO arm, modeled runner lengths in 3D, then 3D-printed test versions shaped around the factory STI oil pan and aftermarket pans from IAG and Killer B Motorsports. Prototypes then ran months of testing. The collector is machined inside to match the 1.75 in primaries and 2 in secondary pipe, so there are no steps in the flow.

Features

1.5 to 1 runner layout, equal within each bank
Low-angle 4-into-1 cast collector for spool and off-boost response
1/2 in flanges at the heads and the up-pipe side
Single-piece mandrel bent 14 gauge 304 stainless runners
Clears the STI oil pan and popular aftermarket pans
No tune required; gaskets and hardware in the box
Manufactured and welded in the USA

Applications

Subaru Baja Turbo: 2004-2006 | 2.5L EJ255
Subaru Forester XT: SG / SH | 2004-2013 | 2.5L EJ255
Subaru Legacy GT: BL / BP | 2005-2009 | 2.5L EJ255
Subaru Outback XT: BP | 2005-2009 | 2.5L EJ255
Subaru WRX: GD / GR / GV | 2002-2014 | 2.0L EJ205 / 2.5L EJ255
Subaru WRX STI: GD / GR / GV / VA | 2004-2021 | 2.5L EJ257

Notes

2002-2005 WRX: manual transmission only, and requires the STI oil pan and pickup. 2006-2007 WRX: requires the STI oil cooler
2004-2008 Forester XT and Baja Turbo need the STI oil pan, pickup and oil cooler. GrimmSpeed lists all Forester XT, Legacy GT, Outback XT and Baja fitments as unconfirmed
Dyno figures quoted here come from a 2010 STI with the stock turbo and basic bolt-ons, running the same tune before and after the header swap
The unequal length EJ header is also sold in the GrimmSpeed Header and Up-Pipe Package with the black GrimmSpeed 2-Bolt EJ25 Up-Pipe

Frequently Asked Questions

Does the GrimmSpeed unequal length EJ header keep the Subaru rumble? Yes. The GrimmSpeed unequal length EJ header was designed to keep the classic boxer rumble. Each bank of runners is equal length, but one bank is 1.5 times longer than the other, which preserves the uneven sound while the equal banks keep equal length performance.
Does this header require a tune? No. GrimmSpeed lists the header as requiring no tune and safe to bolt on. In its dyno testing the same tune stayed loaded before and after the swap, so the header was the only variable. Larger turbos or other power parts carry their own tuning needs.
Will the header fit with an aftermarket oil pan? Yes. During development GrimmSpeed formed the header around the factory STI oil pan and around popular aftermarket pans, including those from IAG and Killer B Motorsports. Some older WRX, Forester XT and Baja fitments need the STI pan and pickup first.
Is an up-pipe included with the header? No. The box contains the header with gaskets and installation hardware only. GrimmSpeed sells a package that pairs this header with its black ceramic coated 2-Bolt EJ25 Up-Pipe, and that up-pipe is also sold separately in raw stainless or black.
Will the header slow spool on a stock turbo STI? Slightly. On a 2010 STI with the factory turbo, GrimmSpeed recorded some loss of spool against the stock manifold, with about 1.6 psi less average boost, but gains of up to 10.3 hp and 23.1 lb-ft. The power curve shifts toward higher rpm.

About GrimmSpeed

GrimmSpeed began in 2006 in a single-stall garage in Maplewood, Minnesota, porting and polishing Subaru manifolds. After building parts for several other makes, the company narrowed its focus back to Subaru, and its range now covers intercoolers, charge pipes, intakes, bypass valves, headers, up-pipes, catback exhausts, turbochargers, brake caliper kits, drivetrain mounts and titanium engine bay parts for the WRX, STI, Forester XT, Legacy GT, Ascent and BRZ, along with the Toyota 86 and GR86. GrimmSpeed engineers and manufactures as much of that range as it can in-house, and its front mount intercoolers are welded and inspected by hand in the USA.

Additional Information

The Bulletproof Automotive website contains many thousands of products purchased in multiple different currencies. All of the prices are entered manually and accurately at the time of entry. Due to the consistently fluctuating international exchange rates, at times prices may not be able to be honored at their original intended rate. We apologize for any inconvenience this may cause, unfortunately our website is unable to compensate dynamically for what can at times be volatile changes in the cost of items due to currency values fluctuating, changes in prices from suppliers, changes in shipping and import duties, and other factors. Rest assured that any order you place on line will be at zero risk to you in this area. If in the event your order cannot be fulfilled at the original intended website price we will offer you a 100% refund, no questions asked. We will continue to do our best to maintain updated prices and we will always continue to offer our price match guarantees as well to ensure our prices are always the best for you. In short, prices may change without notice. It is always advised to give us a call prior to placing your order online to confirm availability and to confirm current pricing.

Shipping Policy

Items that are in stock in the US, either at Bulletproof’s warehouse or at a supplier’s warehouse, are generally delivered within 7-10 days. Special order items from overseas take considerably longer. As a courtesy Bulletproof offers delivery estimates to our customers which take into consideration manufacturer availability and shipping schedule. These estimates represent our best guess based on previous orders from the manufacturer and do not in any way imply a guaranteed delivery window. Many manufacturers work in a “just in time” inventory system and often take 2-20+ weeks to produce an item once an order is submitted. All deliverable items are then sent to our Japanese warehouse. Bulletproof ships a minimum of one full ocean freight container every month from Japan, oftentimes more than one a month. Ocean freight takes an average of 4 weeks. Typically it breaks down to one week in Japan for paperwork and customs, two weeks by boat and one week in US customs/clearance. Due to the wide number of variables between manufacturer and shipping schedules, delivery estimates are simply just that – estimates. We attempt to estimate conservatively and we usually deliver faster than our estimates suggest. It is not Bulletproof’s policy to guarantee delivery time of any special order item, this is impossible for us to do. By ordering you acknowledge that there is no required delivery ETA and an order may not be canceled or altered due to manufacturing or shipping delays, all ETA’s are provided as a best guess only. Please review the full Terms & Conditions here.

BP Pricing Difference

We do pricing a little differently on our JDM brands and we believe in making things simple and clear. No hidden fees or surcharges. Every price you see includes the shipping cost to our office in Los Angeles, California and all the associated taxes/duties/fees for bringing the products into the US. The only shipping you ever pay is from our facility in the US to your location. Be wary of resellers that don’t include the cost of international shipping in their pricing on JDM parts. While we believe we’ll always have the lowest all-in price on JDM products, we offer a price match guarantee for all authentic parts purchased from authorized dealers as well. For many international customers, it’s much more affordable to ship from the USA than from Japan directly, as the air freight and ocean freight costs are typically much less. However, for customers looking to ship directly from Japan outside of North America, or domestically in Japan, we can provide pricing specifically for that scenario. Please do not hesitate to contact us with any pricing questions or concerns. Please email us at sales@bulletproofautomotive.com with any inquiries.

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GrimmSpeed Unequal Length EJ Header for GD / GR / GV / VA Subaru STI and GD / GR / GV WRX [GRM113026]

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GrimmSpeed Unequal Length EJ Header for GD / GR / GV / VA Subaru STI and GD / GR / GV WRX

Development and Testing

Features

Applications

Notes

Frequently Asked Questions

About GrimmSpeed

Reviews