https://www.motor1.com/news/391066/p...-gts-40-spied/
982.2 GTS 4.0 prototype spotted. Allegedly will have a detuned version of the engine from the GT4, making ~400 BHP.
My local Posche dealer seems to be pretty reliable for rumours, as about 6 months ago they told me that the next gen 718 GTS would have the 4.0. They also said the 992.1 Carrera and Carrera 4 would not come with manual transmissions, which has been true so far.
