RM Engineering GT4+ Splitter Kit For F8X M3/4

Engineered for Maximum Performance. Inspired by BMW Motorsport. Proven on Track.

The Ridgeline Motorsport GT4+ Aero Kit is our most comprehensive aerodynamic package for the BMW F8X platform.

Developed from the visual and aerodynamic foundation of the BMW F82 M4 GT4 race car, the GT4+ system evolves beyond the limitations of the original GT4 rulebook. Each component was redesigned using real-world track experience to increase aerodynamic performance while maintaining a balanced relationship between front and rear downforce.

Designed for serious track-day drivers, time attack competitors, and high-performance street builds, the complete GT4+ package combines a reinforced front lip, tunneled front splitter, GT4 canards, and a chassis-mounted rear wing into one integrated aerodynamic system.

Vehicle Fitment

Designed for compatible BMW F8X M models, including:

• BMW F80 M3 Sedan
• BMW F82 M4 Coupe
  

Please confirm your vehicle model, bumper configuration, trunk configuration, and competition-class requirements before ordering.

Track-Proven Development

The GT4+ Aero Kit was developed and tested on road-going BMW F8X vehicles equipped primarily with bolt-on modifications.

Testing results were achieved without extensive vehicle weight reduction and while using 275/35R18 200TW street-class tires.

Recorded F-Chassis Results

Super Lap Battle 2025 — Circuit of the Americas

• Fastest BMW in class, excluding two Toyota Supras

WeatherTech Raceway Laguna Seca

• Best recorded lap: 1:34.341

Global Time Attack Finals — Buttonwillow CW13

• Fourth place
• Best recorded lap: 1:50.940
• Fastest BMW in class, excluding three Toyota Supras

Real-world testing, competition use, and continuous development remain central to every Ridgeline Motorsport aerodynamic product.

GT4+ Front Lip

The GT4+ Front Lip features a reinforced design developed to create a sealed front aerodynamic plane when paired with the GT4+ Tunneled Splitter.

The front lip may also be installed without the lower splitter. However, using the lip without the splitter may reduce its structural support and service life, particularly during track use or contact with road surfaces.

Front Lip Features

• Reinforced GT4-derived design
• Designed to integrate with the GT4+ Tunneled Splitter
• Creates a cleaner transition between the bumper and splitter
• May be installed separately
• Hardware included

GT4+ Tunneled Front Splitter

The GT4+ Tunneled Splitter combines the front lip and lower splitter into a two-piece aerodynamic system.

An integrated airflow channel helps maintain airflow toward the factory lower oil cooler, while the molded tunnel increases aerodynamic surface control, structural rigidity, and front-end performance.

Splitter Features

• Two-piece front lip and splitter system
• Integrated airflow channel for the lower oil cooler
• One-piece molded aerodynamic tunnel
• Designed to increase front-end downforce
• Reinforced construction for improved rigidity
• Installation hardware included
• Minor modification of OEM vehicle components required

Aluminum Skid Block Kit

An aluminum skid block kit is available 

The skid blocks help protect the lower splitter surface from contact with pavement, curbing, driveways, and track surfaces.