RM Engineering GT4+ Kit (F8X M3 / M4)

Ridgeline Motorsport GT4+ Aero Kit

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

OPTIONAL ADD ON BUT NOT INCLUDED: 

• Ridgeline Motorsport MP Style Side Skirt (F8X M3 / M4)
  

Proven Track Performance

The whole Kit is designed to optimize performance for vehicles with bolt-on molds only. The test results are based on Road Going F8Xs with no weight reduction with 275/35/R18 200TW Street Tires Only. F-Chassis Testing Results to Date:

SuperLap Battle 2025 – COTA: P3 – 02:22.320
(Fastest BMW in class, excluding 2 Supras)

GridLife 2025 – Laguna Seca: 1:35.341

Global Time Attack Finals – Buttonwillow CW13: P4 – 01:50.940
(Fastest BMW in class, excluding 3 Supras)

Real results. Real podiums. Real validation.

The Ridgeline Motorsport GT4+ Kit is our ultimate aero package for the BMW F8X platform—developed using the aesthetic foundation of the OEM M4 GT4 and evolved beyond GT4 rule-book limitations. By redesigning every component around real-world data, we’ve created a package that produces significantly increased downforce

Designed to comply with GTA Street Class and GridLife Street Mod regulations, the GT4+ Kit brings professional-level aero to the enthusiast and competitive driver alike.

Included Components

• GT4+ Front Lip

A reinforced, GT4-inspired design that creates a sealed front plane when paired with the splitter.

Can be used without the splitter, though lifespan will be reduced.

• GT4+ Tunneled Splitter

Two-piece lip + splitter system

Integrated airflow channel for the lower oil cooler

1-piece molded tunnel for increased downforce and rigidity

Optional aluminum skid block kit (+$99)

Includes all hardware; minor OEM chassis modification required

• OEM GT4 1:1 Canards

Exact GT4 geometry for improved front-end bite and increased mid/high-speed stability.

• GT4+ Rear Wing

Redesigned chassis-mount solution eliminates the water-leak issue found in the OEM GT4 wing

Maintains OEM structural strength

Larger foil than OEM GT4 (no GT4 rule limitations)
→ More rear downforce with similar aerodynamic efficiency

Why Choose the GT4+ Kit?

Inspired by BMW Motorsport, engineered for maximum performance

Increased downforce front and rear

Balanced aero for serious track performance

Legal for popular street-class time attack series

Modular system—purchase as a full kit or individual components

Notes

Full kit recommended for best aero balance

All hardware included

Splitter skid blocks optional

Professional installation recommended

Installation Info:

GT4+ Splitter Installation PDF

GT4+ Kit Installation Video: Part 1 // Part 2