[autodoctor911]

well, since no one else will give a straight answer, yes the coolant going to the heater core does bypass the thermostat on p-cars, like any other car does, and a low temp thermostat can only reduce the performance of the heater.

may I go ahead and ask the next question?

Has anyone else monitored the coolant temperature on a 987/987 with an actual scan tool, and noticed that it does vary just like the older cars, but the gauge does not move?

I have seen this trend in temp gauges for the last 20 years or so. Porsche and Mercedes were some of the last to have actual temp gauges. Now pretty much every car that has a gauge is lying to you. It is no more effective than an idiot light at telling you what the engine temp is. In fact if it replaces all lights that would indicate a problem with temperature before damage can occur, it is less effective, since it is a lot harder to notice the needle jump from the center position to the top of the range once it gets out of the range that the controller is set to allow while it holds the needle steady in the middle.

P.S.: all M96/M97 cars use the same thermostat which includes 987s and 997s up to 2008, and I'm pretty sure the 9A1 tstat is the same temp but a different housing, or lack there of.

I will say, however that a lower temp thermostat can prevent an engine from running too hot, because by lowering the normal operating temperature of the engine, it will take longer for the temp to rise to dangerous levels when the cooling system's capacity to cool is overcome by higher ambient temperatures or hard use. It will still eventually get too hot under those circumstances.