SKU: 80469280615

UNEQUAL LENGTH HEADER - 04-21 STI, 02-14 WRX, 04-13 FORESTER XT, 05-09 LEGACY GT, 05-09 OUTBACK XT

Sale price$449.55 Regular price$499.50
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Ships within 48 hours · Estimated delivery Aug 7 - Aug 12

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Description

UNEQUAL LENGTH HEADER - 04-21 STI, 02-14 WRX, 04-13 FORESTER XT, 05-09 LEGACY GT, 05-09 OUTBACK XTClassic Subaru Sound with Unparalleled Performance Over the years, GrimmSpeed Engineers have proven that we are capable of manufacturing the highest quality, best performing exhaust components for the Subaru aftermarket. While we might not always be the first to release a certain product, our major advantage is that we can take our time in testing and development, putting the product through countless hours and thousands of miles of testing. This

Classic Subaru Sound with Unparalleled Performance

Over the years, GrimmSpeed Engineers have proven that we are capable of manufacturing the highest quality, best performing exhaust components for the Subaru aftermarket. While we might not always be the first to release a certain product, our major advantage is that we can take our time in testing and development, putting the product through countless hours and thousands of miles of testing. This ultimately ensures that once a component is in your hands, it will be the most-refined version of that product available. The all new GrimmSpeed Unequal Length EJ Header is a perfect example of this.

Our Unequal Length Header for the EJ-Series engines is very much the same. There are countless options out on the market for high-performing equal length header, but if you want to keep that classic Subaru rumble, there aren’t many great options.

The OEM EJ header really hasn’t changed much in the past 20+ years and it shows. The tight geometry and long cross-pipe between the two collectors are not optimized for flow or power. While the smaller diameter and volume may be good for low-end spool, the factory header gets choked out higher in the rev range. Simultaneously, it's known that swapping to a more-equal length manifold with larger diameter runners offers additional performance potential. We set out to create a header that would be the best of both worlds, offering great performance and the unique sound that makes your car unmistakably a Subaru!

While other aftermarket unequal length headers use different runner lengths for each cylinder, our proprietary design utilizes an innovative setup where each bank of runners are equal length, but one set is 1.5 time the length of the other, providing the rumble sound that we all love while maintaining the performance of an equal length setup. We utilize single piece, mandrel bent runners to minimize disturbances to the exhaust gas along with an extremely durable cast 304 stainless steel collector to achieve keep each back of runners truly equal length which would be difficult to accomplish with a 4-into-1 welded collector. The low angle merge this collector makes for faster spool and unbeatable off-boost throttle response. To match this flow, the collector features machined internal diameters to perfectly match the 1 ¾” primary runners and 2” secondary pipe, eliminating unwanted “steps” in the exhaust flow.

As with all of our exhaust components, our Unequal Length Header features ½ inch flanges for both the heads as well as the up-pipe side. These combined with the 14 gauge runner pipes make for extreme durability and heat retention.

We started the R&D process by scanning the underside of of several EJ engine setups using a FARO arm. This allowed us to design and simulate our header in a digital 3D space to find the optimal balance of runner lengths and angles for the best performance possible on an unequal length setup. Next, we were able to 3D-print a variety of different configurations that would allow us to narrow in on the most optimal final design. During this process, we were able to form the header around a variety of different STI oil pan setups, from the factory pan to aftermarket options like those offered by IAG and Killer B Motorsports. After we were satisfied, we made pre-production prototype units that were put through months of punishing performance and longevity testing.

To validate our simulated performance, we did extensive real-world dyno testing comparing our header design to the factory header as well as some of the most popular headers on the market, both unequal length and equal length. For our testing, we used a 2010 STI with the stock turbo and basic bolt-ons as well as our 2020 STI shop car with full GrimmSpeed Stage 3 bolt-ons, E85, and a GrimmSpeed BB500 turbocharger. Throughout all of our testing, we kept the same tune loaded as well, so the only variable was the header that was installed.

The GrimmSpeed Header out spooled the competition’s equal length header by 50rpm while making similar boost levels. Our Header produces more torque than the equal length manifold right out of the gate, producing about 15ftlbs more throughout spool up. At peak, the GrimmSpeed Header was able to produce and extra 2 ft/lbs of torque and an additional 21 hp compared to the equal length setup.

Quick Specs

  • Innovative 1.5 to 1 Unequal Length Runners - Each bank of runners is equal length, allowing for equal length performance with an unequal length sound
  • 4-into-1 Low-Angle Merge Cast Collector - Ensure minimal restriction and maximum performance
  • Smooth, Restriction-Free Flow Throughout – Single piece mandrel bent tubing welded to a single piece merge collector removes unwanted “steps”
  • Substantial Power/Torque Gains - +25hp and +25ft/lbs of torque over stock
  • Quickest Spooling Aftermarket Header - Faster spool and more power compared to the competition
  • No Tune Required – Safe to run, just bolt on
  • Gaskets and Hardware Included – Everything you need to get installed and on the road
  • Designed To Fit With Aftermarket Oil Pans - Fits with the STI oil pan or popular aftermarket options
  • Full 304 Stainless Steel Construction - 1/2" flanges and 14ga runners for extreme durability
  • Manufactured and Welded In The USA – For consistency and top quality control

Fitments

  • 04-21 Subaru STI
  • 08-14 Subaru WRX
  • 09-13 Subaru Forester XT*
  • 05-09 Subaru Legacy GT*
  • 05-09 Subaru Outback XT*
  • 02-05 Subaru WRX 5MT (Requires STI Oil Pan and Pickup)
  • 06-07 Subaru WRX (Requires STI Oil Cooler and Feed Pipe)
  • 04-08 Subaru Forester XT* (Requires STI Oil Pan, Pickup, and Oil Cooler)
  • 04-06 Subaru Baja XT* (Requires STI Oil Pan, Pickup, and Oil Cooler)
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 80469280615

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Chanell Anderson
West Palm Beach, US
★★★★★ 5
Beautiful Gift
Size: Classic Cozy Collection, Color: "Thank You" Card
Beautifully packaged gift box. We got it for my son’s 1st grade teacher and she loved it. Great quality and presentation, thank you.
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Reviewed in the United States on May 23, 2026
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Lexington, US
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LadyRN
Waukegan, US
★★★★★ 5
Heartfelt Gesture of Appreciation
Size: Classic Cozy Collection, Color: "Thank You" Card
The Unboxme Thank You Gift Box proved to be the epitome of a thoughtful and appreciated gift. I recently chose this box as a thank you gift for my mother-in-law, and it was met with genuine delight and gratitude. The Warm + Cozy theme of the box was not just a label; it encapsulated the essence of the carefully curated items within. From the moment she opened the box, my mother-in-law was greeted with an array of cozy delights that radiated warmth and care. The inclusion of quality items, such as a plush blanket, scented candle, and gourmet treats, showcased the attention to detail in selecting items that truly contribute to a cozy and comforting experience. The blanket, in particular, was not just a token gesture but a genuinely luxurious addition that she immediately embraced. The packaging was not only aesthetically pleasing but also conveyed a sense of thoughtfulness and care in the presentation of the gift. The attention to detail in the arrangement of items and the quality of the box itself elevated the entire unboxing experience. What made this gift even more special was its versatility. The Warm + Cozy box is suitable for various recipients, including clients, coworkers, bosses, neighbors, and employees. Its universal appeal speaks to its well-rounded selection of items that can bring joy to a wide range of individuals. In conclusion, the Unboxme Thank You Gift Box for Women, Warm + Cozy edition, is more than just a collection of items; it's a gesture of genuine appreciation and care. My mother-in-law's positive reaction is a testament to the success of this thoughtful gift. Highly recommended for anyone looking to express gratitude with a touch of warmth and coziness.
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Stephen W
Carnegie, US
★★★★★ 5
Big hit present for mom.
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My wife of 59years loved this gift. She said it was such a thoughtful gift. She is a tea lover too. This was not flowers or clothes so big surprised.
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Richard Lang
San Leandro, US
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Very nice care basket!
Size: Classic Cozy Collection, Color: "Get Well Soon" Card
I really liked the quality of the mug. I gave this as a gift! I wanted to buy it for myself too! The tea and honey looked like good quality!
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Reviewed in the United States on April 24, 2026

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