improve overall downforce of the APR Evolution EVIL-R Widebody Aero Kit, the rear carbon fiber diffuser helps keep the EVIL-R planted through the turns. Diffusers work in conjunction with other aerodynamic components of a car to help produce downforce. Because a car displaces air as it moves forward, the air molecules in the rear of the car get disrupted causing a vacuum of low pressure air. To help channel the high speed air flow coming from underneath the car, diffusers redirects the high speed air flow to transition smoothly transition into the low pressure vacuum in the rear. This encourages a smoother flowing air flow underneath the car and allows better performance from other aerodynamic components such as aerodynamic wings. This is not a direct bolt-on will require cutting and  modifying the rear bumper.