Does the Super Turbo Muffler for GDB fit a 2004 to 2007 US STI?

Yes. HKS USA lists part 31029-AF001 for the 2004 to 2007 Impreza WRX STI with the EJ257. HKS Japan catalogs the same part for the Japanese-market GDB applied models E to G, built from June 2004 to June 2007, so owners unsure of their exact car should contact Bulletproof Automotive first.

Will it fit the non-STI Impreza WRX?

No. HKS lists part 31029-AF001 for the Impreza WRX STI only, and the non-STI WRX sedan of the same generation is not listed. Owners who are unsure which version of the Impreza they have should check the model code on the chassis plate before ordering.

How loud is it compared to stock?

HKS measured 91 dB on its close test against 84 dB for the factory system, on the Japanese-market GDB STI with the EJ20. HKS designs each Super Turbo Muffler around its engine and to meet the JASMA standard, and the Super Turbo Muffler for GDB carries certification 03S15238.

Does it suit an STI with an upgraded turbo?

Yes. HKS developed the Super Turbo Muffler range to stay effective from stock cars up to cars with upgraded turbines, so it can stay on the car as a build grows. Owners adding more boost may also want the HKS S-Type Intercooler Kit for GDB.

How much ground clearance does it leave?

HKS lists 118mm of minimum clearance on stock suspension, with the center resonator as the lowest point. Owners on lowering springs or coilovers, such as the HKS HIPERMAX S for GDB, should check the gap under the center resonator before regular use.

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Description

HKS Super Turbo Muffler for GDB Subaru Impreza WRX STI

HKS’s Super Turbo Muffler for GDB Subaru Impreza WRX STI is a SUS304 stainless cat-back for the 2004 to 2007 EJ257 sedan, running a 75mm pipe from the factory front pipe through a center resonator to a single main muffler with a 124mm tail. HKS measured 91 dB on its close test against 84 dB for the factory system, so the STI sounds clearly sportier than stock. It suits the owner replacing a tired factory system on a GDB that may see more power later.

Development and Testing

HKS developed the Super Turbo Muffler range to combine exhaust efficiency with lower sound pressure, to stay effective from stock cars up to cars with upgraded turbines, and to give each engine its own exhaust note while meeting the JASMA standard. HKS developed and certified the Super Turbo Muffler for GDB cars on the Japanese-market STI with the 2.0L EJ20 turbo, applied models E to G.

Features

Cat-back from the factory front pipe, with a center resonator
75mm pipe throughout
Single main muffler with a 124mm tail
SUS304 stainless steel
Reuses the factory spherical gasket, spring bolts and rubber hangers

Specifications

Center Pipe Diameter: 75mm
Tip: 124mm, single
Main Material: SUS304 stainless steel
Sound Level, Factory System: 84 dB, HKS measurement
Sound Level, HKS: 91 dB, HKS measurement
Minimum Road Clearance: 118mm at the center resonator, stock suspension
Certification Number: 03S15238

Applications

Subaru Impreza WRX STI: GDB | 2004-2007 | EJ257

Notes

HKS Japan lists this part for the GDB applied models E to G, built from June 2004 to June 2007, and HKS USA lists it for the 2004 to 2007 US STI
Sound figures and certification are HKS results on the Japanese-market GDB STI with the EJ20
Not listed for the non-STI Impreza WRX
HKS lists 19.8kg (43.7lb) with the packing dimensions and does not publish a separate product weight
HKS notes that hangers, brackets and stays may change without prior notice

Frequently Asked Questions

Does the Super Turbo Muffler for GDB fit a 2004 to 2007 US STI? Yes. HKS USA lists part 31029-AF001 for the 2004 to 2007 Impreza WRX STI with the EJ257. HKS Japan catalogs the same part for the Japanese-market GDB applied models E to G, built from June 2004 to June 2007, so owners unsure of their exact car should contact Bulletproof Automotive first.
Will it fit the non-STI Impreza WRX? No. HKS lists part 31029-AF001 for the Impreza WRX STI only, and the non-STI WRX sedan of the same generation is not listed. Owners who are unsure which version of the Impreza they have should check the model code on the chassis plate before ordering.
How loud is it compared to stock? HKS measured 91 dB on its close test against 84 dB for the factory system, on the Japanese-market GDB STI with the EJ20. HKS designs each Super Turbo Muffler around its engine and to meet the JASMA standard, and the Super Turbo Muffler for GDB carries certification 03S15238.
Does it suit an STI with an upgraded turbo? Yes. HKS developed the Super Turbo Muffler range to stay effective from stock cars up to cars with upgraded turbines, so it can stay on the car as a build grows. Owners adding more boost may also want the HKS S-Type Intercooler Kit for GDB.
How much ground clearance does it leave? HKS lists 118mm of minimum clearance on stock suspension, with the center resonator as the lowest point. Owners on lowering springs or coilovers, such as the HKS HIPERMAX S for GDB, should check the gap under the center resonator before regular use.

About HKS

HKS is a Japanese performance engineering brand founded in 1973 and headquartered in Fujinomiya, Shizuoka, with a long-standing reputation for developing high-quality aftermarket parts and motorsport-proven technology for enthusiast and professional applications. Known for innovations in turbocharging and engine performance, HKS produces a broad range of components including exhaust systems, turbo kits, electronics / engine management, and suspension solutions, with product development heavily influenced by decades of involvement in racing disciplines such as circuit time attack, drag, and drifting.

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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HKS Super Turbo Muffler for GDB Subaru Impreza WRX STI [31029-AF001]

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HKS Super Turbo Muffler for GDB Subaru Impreza WRX STI

Development and Testing

Features

Specifications

Applications

Notes

Frequently Asked Questions

About HKS

Reviews