Porsche GT4 Clubsport and Clubsport MR: Two Race Cars Derived from the Porsche Cayman Coupe Published on September 28, 2016 in First Drives by Gabriel Gélinas Photo: Gabriel Gélinas Porsche GT4 Clubsport MR - The conversion kit developed by Manthey Racing includes carbon fibre hood and doors, as well as a polycarbonate bumper and side windows.