Ultra Racing Side Lower Brace for Subaru Impreza WRX STI

The Ultra Racing UR-SD8-1337P 8-Point Side Lower Brace is a vehicle-specific chassis reinforcement upgrade developed for the third-generation Subaru Impreza WRX STI GR/GV platform.

Rather than increasing spring or anti-roll-bar stiffness, a chassis brace works by reinforcing the structure connecting suspension and body mounting areas. Reducing unwanted movement through the floor and lower chassis can help the suspension operate from a more stable platform.

For drivers using their Impreza WRX STI enthusiastically on UK roads, track days or with modified suspension, this can contribute to a more precise and consistent chassis response.

Improved Chassis Rigidity

During cornering, braking and acceleration, the vehicle shell is subjected to torsional forces. Although the Impreza WRX STI has a comparatively stiff platform from the factory, additional chassis reinforcement can be beneficial when the car is fitted with:

• Lowering springs
• Performance dampers
• Coilovers
• Higher-grip road tyres
• Track-focused tyres
• Upgraded anti-roll bars
• Increased engine performance

The Ultra Racing side lower brace connects multiple areas underneath the vehicle to help reduce relative movement between chassis mounting points.

The result is intended to provide a more solid platform for the suspension, helping improve steering response and consistency during fast directional changes.

8-Point Chassis Reinforcement

The SD8 designation identifies the brace as an 8-point side/lower reinforcement system.

Rather than relying on a single cross brace, the system spreads reinforcement across multiple mounting points along the underside of the vehicle.

Ultra Racing’s official catalogue lists UR-SD8-1337P as a:

Side Lower Bar / Side Floor Bar

for Subaru Impreza / WRX STI applications.

This configuration makes it particularly useful for cars where improved torsional rigidity is desired without substantially altering suspension geometry.

Performance Benefits

When installed as part of a properly set-up chassis, the Ultra Racing side brace can help provide:

• Reduced chassis and floor flex
• More consistent suspension response
• Improved steering feedback
• More predictable cornering behaviour
• Improved chassis stability during hard braking
• Better response during rapid direction changes
• A more connected feel between front and rear suspension

Chassis braces do not increase engine power or directly increase mechanical grip. Their purpose is to give the suspension a more rigid platform from which to operate.

Ideal for Fast Road and Track Builds

The UR-SD8-1337P is particularly appropriate for:

Fast road WRX STI builds
Adds chassis reinforcement without converting the vehicle into an excessively harsh track-only setup.

Lowered vehicles
Useful where lowering springs or coilovers transmit greater forces into the chassis.

Track-day vehicles
Additional rigidity can help maintain more consistent suspension behaviour during repeated high-load cornering.

High-grip tyre setups
Modern performance tyres generate significantly higher cornering forces, increasing load through the chassis.

Modified WRX STI builds
A logical chassis upgrade alongside strut braces, anti-roll bars, lower braces and upgraded suspension.

Construction

Ultra Racing specialises in steel chassis reinforcement components and is known for using rigid welded construction and vehicle-specific mounting arrangements.

Available product catalogues for UR-SD8-1337P identify:

• Steel construction
• White finish
• Vehicle-specific design
• Side/lower chassis mounting position

The product is not a universal brace and should only be fitted to compatible vehicles.

Installation Information

Professional installation is recommended.

The vehicle will normally need to be raised securely to access the underside and mounting locations. All mounting points should be checked before installation and bolts tightened using appropriate procedures and torque specifications.

Because many WRX STI vehicles are now modified, customers should check for possible interference with:

• Aftermarket exhaust systems
• Large downpipes or centre sections
• Undertrays
• Floor modifications
• Custom chassis reinforcement
• Non-standard suspension or subframe components

Always confirm compatibility using the vehicle chassis/VIN and existing modifications before ordering if there is any doubt.

4. Key Features

• Genuine Ultra Racing chassis reinforcement product
• Manufacturer reference UR-SD8-1337P
• 8-point side/lower chassis brace design
• Designed for Subaru Impreza WRX STI GR/GV generation
• Reinforces the lower floor/chassis structure
• Helps reduce unwanted chassis flex
• Can improve steering response and chassis feedback
• Supports more consistent suspension operation
• Suitable for fast road and track-day vehicles
• Excellent companion upgrade for coilovers and lowering springs
• Steel construction
• Distinctive Ultra Racing white finish
• Vehicle-specific rather than universal design

5. Technical Specifications

Manufacturer: Ultra Racing
Manufacturer Part Number: UR-SD8-1337P
SKU: UR-SD8-1337P
Product Type: Side Lower Brace / Side Floor Brace
Brace Configuration: 8-point
Vehicle Position: Lower side / floor chassis area
Material: Steel
Finish: Ultra Racing white
Application: Vehicle-specific
Primary Vehicle Platform: Subaru Impreza WRX STI GR/GV generation
Installation: Bolt-on chassis reinforcement where original mounting locations permit
Intended Use: Fast road, performance and track-day chassis reinforcement

Not reliably published

Ultra Racing’s available catalogue information does not provide a reliably verifiable product weight, tubing diameter or exact wall thickness for UR-SD8-1337P, so these specifications should not be added to the WooCommerce listing unless confirmed directly by Ultra Racing.

6. Vehicle Fitment / Compatibility

Verified application family

Ultra Racing lists UR-SD8-1337P for the Subaru Impreza / WRX STI third-generation GR platform, while additional Ultra Racing catalogue information also lists the same brace for the related GV sedan platform.

For the UK market, the relevant factory Type UK performance models use the 2.5-litre turbocharged EJ257 boxer engine.

UK applications to target

Subaru Impreza WRX STI Type UK – GR-series Hatchback
2.5 Turbo EJ257

Subaru Impreza / WRX STI Type UK – GV-series Saloon
2.5 Turbo EJ257

Important chassis-code note

Many overseas listings refer to this product as fitting GRB and GVB. These codes are frequently associated with Japanese-market 2.0-litre STI variants.

UK-market 2.5-litre Type UK vehicles may carry different derivative/model identifiers within the same GR/GV body platform.

For this reason, customers should provide the registration or chassis/VIN if exact compatibility needs confirming before purchase.

The fitment below deliberately excludes ordinary Impreza models, diesel models, non-STI models and later VA-generation WRX STI vehicles because these cannot be confidently verified for this part number.

Frequently Asked Questions

Does the Ultra Racing UR-SD8-1337P fit a Subaru Impreza WRX STI?

Yes. Ultra Racing lists UR-SD8-1337P as a side lower/floor brace for the third-generation Subaru Impreza WRX STI platform. GR hatchback and GV sedan applications are documented. Exact compatibility should still be checked against the vehicle chassis/VIN before ordering.

Does UR-SD8-1337P fit a UK WRX STI Type UK?

The relevant UK WRX STI Type UK models use the GR/GV-generation chassis architecture and 2.5-litre EJ257 engine. However, UK derivative codes can differ from the GRB/GVB terminology used in overseas Ultra Racing catalogues. We therefore recommend VIN or registration confirmation before ordering.

What does an Ultra Racing side lower brace do?

The brace connects several lower chassis mounting points to reduce unwanted movement and torsional flex through the vehicle floor. This gives the suspension a more rigid structure from which to work.

Will a chassis brace make my WRX STI handle better?

It can improve chassis response and consistency rather than directly increasing tyre grip. Drivers may notice improved steering feedback, sharper responses and a more solid feeling during hard cornering and braking.

Is UR-SD8-1337P an 8-point brace?

Yes. Ultra Racing markets UR-SD8-1337P as an 8-point side/other or side lower brace, with the SD8 designation corresponding with this mounting arrangement.

Is this suitable for a WRX STI running coilovers?

Yes. Chassis reinforcement is particularly useful alongside stiffer suspension because coilovers and performance tyres can transmit greater loads through the vehicle shell.

Does this brace fit a normal Subaru Impreza?

Do not assume so. The strongest manufacturer evidence is for Impreza WRX STI GR/GV applications. Compatibility with ordinary Impreza, RX, WRX, diesel or naturally aspirated models should be independently confirmed before purchase.

Will the brace fit with an aftermarket exhaust?

Usually the brace uses established chassis mounting locations, but exhaust routing varies considerably between aftermarket systems. Clearance should therefore be checked where the car has a modified exhaust, downpipe or underbody components.