2020 Porsche 718 Cayman GT4 Review by The Straight Pipes. The Cayman GT4 is pumping out 414hp and 309 lb-ft tq from a 4L flat 6 cylinder engine. Sitting at $148,205 CAD, would this be your pick over the C8 Corvette, Porsche 718 Spyder, Porsche 911 GT3 lol?