QA1 HD03-12300 PromaStar Double-Adjustable Front Coilover Strut Kit 300lb/in Handling

The QA1 HD03-12300 PromaStar Coilover Strut Kit is a complete front suspension upgrade featuring double-adjustable coilover struts, tuned 300 lb/in springs, and aluminum caster/camber plates. Engineered for drivers who demand precise, tunable handling performance from both street driving and track use, this kit delivers a major upgrade over stock suspension in ride quality, handling response, and stance.

At the heart of the PromaStar system is an inverted cartridge strut design. Unlike conventional strut designs, the large-diameter shaft resists side loading during hard cornering and braking, resulting in smoother, more consistent damping performance. The lightweight threaded aluminum body reduces unsprung weight, improving suspension responsiveness and traction.

The double-adjustable valving system allows independent tuning of compression and rebound damping via a single, easy-to-reach 18-position knob located at the top of the strut tower under the hood — no need to get under the car. Pressing the knob adjusts compression; pulling it adjusts rebound, with each setting independently configurable for maximum flexibility across driving conditions.

Ride height is fully adjustable via the fully threaded strut body, offering 0 to 2 inches of lowering relative to stock — ideal for dialing in stance for shows or optimizing center of gravity for the track. Included aluminum caster/camber plates feature a durable anodized finish for corrosion resistance and allow precise front-end geometry adjustment to reduce tire wear and sharpen handling.

Kit Includes:

• One pair of double-adjustable inverted PromaStar coilover struts
• One pair of 300 lb/in powder-coated springs
• Aluminum caster/camber plates
• All required mounting hardware

Key Features:

• Inverted strut design — large-diameter shaft resists side loading for consistent cornering and braking performance
• Double-adjustable damping — 18-position independent compression and rebound tuning via top-mounted knob
• 300 lb/in spring rate — tuned for handling-focused street and track applications
• Ride height adjustability — 0–2 inches of lowering via threaded collar
• Lightweight aluminum construction — reduces unsprung weight for improved suspension response
• Aluminum caster/camber plates — anodized finish, precision geometry adjustment
• Bolt-in installation — installs in factory mounting locations with basic hand tools; no toe link relocation required
• Dyno-tested and serialized — each kit individually tested for quality control
• Fully serviceable and rebuildable — supported by any QA1 authorized service center
• Made in the USA — manufactured in Lakeville, Minnesota

Whether the goal is an aggressive daily driver, autocross competition, or road course performance, the QA1 HD03-12300 PromaStar kit provides the tunability and build quality to match any driving style. Each kit is dyno-tested and serialized at QA1's Lakeville, Minnesota facility for verified performance and full serviceability.