F8x M3/M4 Big Fin Performance Carbon Fiber Rear DiffuserTired of the understated factory diffuser look? This performance carbon fiber diffuser steps up the game with prominently enlarged center fins that give your M3 M4 the aggressive edge you've been wanting. It delivers that coveted OEM plus aesthetic for drivers who refuse to compromise on style. Maximize its impact by pairing it with bumper extensions or a rear trunk spoiler for a fully integrated, head turning rear design. Fits: 2015 2019 F80 M3 2015