In reading the concerns over some of the units producing extra heat, I wonder if anyone has identified the root cause. Using heat wrap on the exhaust, heat tape and heat shields are band-aids that simply mask the root cause. If the spark plugs are running ghost white then we know it is calibrated very lean. As I understand it, the 2013s have a catalytic converter that previous models did not have? And the 2013s have the added panels that fill in the gaps along the sides, further reducing the airflow? There is likely a new ECU program for fuel and ignition that goes with the CAT, so based on the heat and the plug color it should be a safe guess that there were new targets for emissions and reduced fuel consumption, with the lean calibration now causing the extra heat issues? Fuel is a great coolant, so cutting back on the fuel delivery will for sure make the engine run hotter. We would also want to validate the cooling system is filled to capacity. Maybe the cooling system now needs more cooling capacity to compensate for the reduced cooling effect of less fuel? Not just the amount of liquid capacity, but overall cooling capability of the entire cooling system, from pump to water flow to radiator efficiency to fan timing, all of it.
I would really want to see what kind of fuel is being used on the units that are reporting the extra heat. Are they all burning 10% ethanol, or maybe more? It would be most curious to see what happens if one were to run a tank of premium, non-oxygenated fuel to see if it makes a difference. Could the “hot” units be even worse due to higher levels of ethanol (more leaning out of the fuel-air mixture) than simply magnifies the problem?
My guess would be a new ECU program as being the single most effective solution, but that takes time to develop and validate. Meanwhile, it stands to reason to use non-oxygenated fuel as much as possible. A colder spark plug also makes sense. And the heat shields and tape and wrap should protect components while this all gets sorted out.