Mugen FL5 GROUP B Carbon Fiber Rear Bumper Diffuser

Pre-Order Now Available - ETA at Mugen Japan (Late March).
This part will ship to King Motorsports at that time. 
FULL NON-REFUNDABLE PAYMENT IS REQUIRED AT TIME OF PURCHASE TO SECURE GROUP B MUGEN PARTS. THIS GROUP B PART WILL NOT BE STOCKED AND IS ONLY MADE TO ORDER AT MUGEN. 

The Mugen FL5 Group B Carbon Fiber Rear Bumper Diffuser is the definitive aerodynamic solution for managing airflow at the rear of the 11th Gen Civic Type R. Developed through rigorous aerodynamic analysis, this diffuser features a large, optimized profile designed to rectify airflow coming from the underbody, significantly increasing rear-end downforce and high-speed stability. A key technical innovation is the integrated opening at the top of the diffuser; this vent allows high-pressure air trapped inside the rear bumper to be released efficiently, drastically reducing drag and parachute-effect air resistance that often plagues performance hatchbacks on the circuit.

Crafted from premium Carbon Fiber Reinforced Plastic (CFRP), this diffuser is a cornerstone of Mugen’s "Extreme R" philosophy, emphasizing both lightweight construction and functional racing spirit. The component sits approximately 22mm lower than the factory rear under spoiler, providing a more aggressive, ground-hugging aesthetic while sealing the rear aerodynamic path. It is specifically engineered for simultaneous installation with the Mugen Sports Titanium Exhaust System, ensuring a perfect fit and a cohesive, professional-grade finish. For the FL5 owner seeking the absolute limit of functional Japanese aero, this Group B rear diffuser is an essential final piece of the aerodynamic puzzle.