Agree that we are largely saying the same thing, just coming at it from a different angle and choosing language to highlight or respective points of view. Although I find your last statement about choosing not to "unleash the 2.5" to be very optimistic and little more than hyperbole. Remember the base engine in the Carrera has an extra two cylinders, an extra 500 cc, and an extra turbocharger. I'm sure it could more than hold it's own against an "unleashed 2.5".I was not disagreeing with you, I was adding to your point. There is no model of 911 that is not allowed to outperform another. Conversely, every model of 718 is not allowed to outperform an otherwise comparable 911. Porsche has no desire to produce a maximum performance car that does not say “911” for the general Porsche consumer. The level of performance that exceeds the 911 line is reserved for exorbitant hypercars. I don’t think it’s as much a model line strategy as it is an effort to protect an aged design. The original Boxster was considered underpowered, so it was never a threat to the monster Turbo models of 911. That is no longer true.
The problem with comparing Porsche sports cars to other manufacturers’ model strategy is that Porsche does not market average cars. Everything they sell is marketed as The Best. They try to have it both ways. They make the best 911. They do not make the best 718.
It could also be argued that the motivation behind the 4.0 GTS was less about sound, and more about deciding not to unleash the 2.5. Marketing sells what senior management decided to make, not the other way around.