Flatout Suspension 15-23 Ford Mustang [GR40] GR4-1523MUSTANG

DISCLAIMER: This is a made to order item. The lead time for this product is 4-8 weeks.

Flatout GR40 Coilovers for 2015–2023 Ford Mustang

The Flatout GR40 Coilovers are engineered for drivers who demand motorsport-grade suspension performance with the durability required for rally and aggressive driving. Designed with 0–2 inches of adjustable ride height, the GR40 system allows precise tuning for tarmac, gravel, or rallycross conditions while maintaining stability and chassis balance.

Built with inverted front shocks for maximum strength and external reservoir rear shocks (on select applications) for improved cooling and endurance, the GR40 system is designed to withstand harsh terrain and repeated high-speed impacts. Combined with proprietary rally valving and bypass piston technology, this suspension provides smooth compliance at low speeds and exceptional control when pushing the vehicle harder.

Key Features

• 0–2” Adjustable Ride Height → Dial in stance and ground clearance for rally or aggressive driving

• Inverted Front Shocks → Increased durability and reduced flex under extreme conditions

• External Reservoir Rear Shocks (Application Dependent) → Improved cooling and fade resistance during extended driving

• Proprietary Rally Valving with Bypass Pistons → Comfort at low speeds with precise control at higher speeds

• Soft Rate LPS 2.5 ID Linear Springs → Balanced ride quality and performance

• OEM-Style Top Mounts → Maintains quiet operation with reduced NVH

• Electroplated Shock Bodies → 7–10 years of corrosion resistance

• Rebuildable Coilover Design → Fully serviceable for long-term performance

• 1-Way Rebound Adjustment → 20 points of damping adjustment for precise tuning

• 3-Year Warranty → Built with durability and reliability in mind

Why Choose the GR40 Coilovers?

Built for Competition
Engineered specifically for rally, rallycross, and motorsport applications where suspension durability and precision are critical.

Superior Handling and Stability
Advanced valving and inverted shock construction provide better chassis control across gravel, tarmac, and mixed surfaces.

Performance Without Compromise
Delivers the control expected from a race-ready suspension while remaining comfortable during daily driving or transit stages.

Serviceable and Customizable
Fully rebuildable design with customizable spring rates allows drivers to tailor suspension performance to their setup.

FITMENT

2015–2023 Ford Mustang (S550 chassis)
Compatible with applicable trim levels and configurations.