Product Details
The Riaction GP1 Coilovers for the 2017+ Lexus IS350 deliver a premium, adjustable suspension upgrade built for drivers who want more from their IS350 than the factory setup can offer. These Lexus IS350 coilovers are engineered to pair street comfort with canyon and track capability, giving you the stance, handling, and adjustability you've been chasing without compromising daily driveability.
GP1 Series Technology: The GP1 uses a digressive piston design that delivers firmer low-speed damping for flatter cornering and sharper response, while softening at higher shaft velocities to absorb bumps. If you want more control than a linear coilover without sacrificing ride quality, this is the set.
Every GP1 set features a monotube damper with 32 levels of damping adjustment, so you can tune ride quality to match the road, the weather, or your driving mood. Full-length ride-height adjustment separates preload from ride height — meaning you can drop the IS350 to the height you want while preserving spring travel and shock stroke. Riaction coilovers for the 2017+ Lexus IS350 are fully rebuildable and backed by a 2-year warranty, making the GP1 a long-term suspension investment rather than a disposable upgrade.
GP1 Series Technology
- Monotube linear damper with seamless 52mm electroplated carbon steel body
- 32-level damping adjustment (1-Way)
- 44mm CNC-machined 6061 aluminum high-flow piston
- 20mm piston rod for MacPherson applications / 14mm for non-MacPherson
- SAE9254 cold-wound linear main springs
- Multi-thickness valving shims for consistent damping
- Polyurethane oil seals and 7.5W suspension fluid
- Low-gas-pressure design for improved compliance
- Fully rebuildable — built to be serviced, not replaced
Features
- Full-length ride-height adjustment (preload-independent)
- 32 levels of damping adjustment
- Optional Swift Springs upgrade (sold separately)
- 2-year limited warranty
The GT1 uses a linear piston — good low-speed control for body roll, turn-in, and weight transfer, with damping that follows a predictable curve through bumps. That balance makes it the right call for street, canyon, and occasional track days. The GP1 runs a digressive piston that sharpens low-speed response with higher initial resistance for flatter cornering, then softens at higher shaft velocities — a blow-off behavior that relieves harshness over potholes, curbs, and expansion joints. The GP1 is built for track-focused driving, autocross, and aggressive street use where you want the extra bite under load.
Short version: choose GT1 if you want the best daily-street-track balance — typically in stock and ship-ready. Choose GP1 if you want tighter response under load and don't mind the lead time on a built-to-order digressive tune.
Specifications
| Part Number | LX-016-SS |
| Part Name | Riaction GP1 Coilovers |
| Vehicle | 2017+ Lexus IS350 |
| Drivetrain | RWD |
| Adjustment Type | 1-Way |
| Ride-Height Adjustable | Yes |
| Spring Rate - Front | 12 Kg/mm |
| Spring Rate - Rear | 8 Kg/mm |
| Top Mounts - Front | OEM |
| Top Mounts - Rear | OEM |
| Camber Plates - Front | No |
| Camber Plates - Rear | No |
| Suspension Design - Front | True Coilover |
| Suspension Design - Rear | Divorced |
| Notes | Fork FLM |
Vehicle Fitment
- 2017 Lexus IS350
- 2018 Lexus IS350
- 2019 Lexus IS350
- 2020 Lexus IS350
- 2021 Lexus IS350
- 2022 Lexus IS350
- 2023 Lexus IS350
- 2024 Lexus IS350
- 2025 Lexus IS350
- 2026 Lexus IS350