2018 Porsche 718 Cayman GTS - Porsche pumps up the 718 Cayman with the GTS. It appears that Porsche is keen to give the 718 model line more muscle. Months ago, the 718 Boxster was spotted sporting the high-performance GTS treatment. Now, it's the turn of its tin-top counterpart, the 718 Cayman. With that, the pumped up 718 Cayman gets a host of aero tweaks and, possibly, a horsepower figure near the 400 PS range.