The Porsche 718 duo comprising the Cayman and Boxster have been spotted undergoing tests, with the former running road trials and the latter seen testing at the Nurburgring Nordschleife. These here are the GTS variants, which are both expected to make their debuts later this year.

First, the Cayman. Bearing the GTS badge, the fixed roof two-seater will sit at the top of the mainstream series production Cayman range as is the case with the Boxster and the 911, barring the more specialised, motorsport division-developed models such as the Cayman GT4 and 911 GT3 and GT3 RS.

The duo’s series production roots mean they will each run an augmented version of the 718 Cayman S/Boxster S powerplant, which means it will be an uprated version of the 2.5 litre turbocharged flat-four unit; output gains are estimated to be an additional 25 to 30 hp, for peak outputs of around 375 hp to 380 hp. If history dictates form, the Cayman will have marginally higher numbers.

Driveline options could include both a manual and a seven-speed PDK dual-clutch gearbox, with a limited-slip differential and torque vectoring expected to feature on both cars, either optionally or as standard. Sport Chrono can be expected here too, with the rotary drive mode switch on the steering wheel.

Chassis upgrades can be expected to include a slightly lower ride height along with uprated springs and/or dampers, with the option for Porsche carbon-ceramic brakes (PCCB) apparently present on the Cayman GTS test mule here. Upsized wheels and tyres could feature here too.

In terms of styling, the GTS treatment brings a more squared-off look to the front bumper and rear diffuser sections, the former with deeper and larger intakes as well as a chin spoiler. Around the back, the rear bumper similarly has deeper and more squared-off sculpting, while the exhausts exits remaining as before.

As mentioned earlier, these GTS variants are expected to be the top of the mainstream range, while those craving for a more motorsport flavoured, mid-engined Porsche can wait for what appears to be the upcoming Cayman GT4 RS.

GALLERY: Porsche 781 Cayman GTS test mules

GALLERY: Porsche 718 Boxster GTS test mule

GALLERY: Porsche Cayman GT4 RS spyshots