Carbon Fiber Airbox Lid. Prepreg Carbon Fibre Engine cover Our E9X M3 Airbox lid is a direct replacement for the OEM plastic version. Crafted from Prepreg Carbon Fibre it allows for more intake sound to be heard as compared to the OEM lid. Available in black carbon and coloured kevlar options. The fitment is perfect and secured in the same way as the stock part. *By request/order.