Porsche is not stupid enough to kill the golden goose. There is no way Porsche will build a Cayman Turbo with more power than the Cayman S because it will kill the sales of the new 991 Carrera.
It's simple marketing. Porsche has been holding back Cayman ever since it was built even though it is a more capable car due to the mid-engine layout. They've kept both the engine and the suspension inferior deliberately so people would have to keep buying the 911 series over it.
The Cayman R was a let down. I was expecting that car to come out with a serious Mezger engine. It would have sold a lot with a high revving 3.4L Mezger with around 350hp.
2013 E92 ///M3 Space Grey w/ Fox Red
M Performance Exhaust, KW Sleeve Over Kit, and cosmetic upgrades