I have not had any success using the thermal coatings on the piston crown and inside the exhaust ports on highly developed two strokes.   I have had some success using them on the 4 strokes.

Looking at the underside of the two stroke piston shows that the thermal barriers does indeed reduce the amount of heat absorbed into the piston crown but the surface of the thermal barrier carries enough heat to the next compression/ignition cycle to cause pre-ignition.  Squish clearance, compression ratios, ignition timing, fuel octane rating and combustion chamber design was optimized to reduce pre-ignition when thermal coatings were added to the piston crowns.  When we found a design that did not have a pre-ignition problem, power was less than the original un-coated piston crown engine combination.

Thermal coating the inside of the exhaust port helps keeps some of the exhaust heat from entering the cooling system through the exhaust port tunnel walls.  The high surface temperature of the thermal coating radiates and conducts too much heat into the over-scavenged fresh charge in the exhaust port that eventually gets pushed back into the cylinder by the turned exhaust.  Adding any additional heat to this fresh charge in the exhaust port, reduced charge density and resulted in a power loss and was more apt to have detonation on the highly developed engines. 

The thermal barriers when used on 4 strokes pistons have one more engine revolution to cool off and do not carry enough heat to next power cycle to cause pre-ignition.

We found that the thickness of the thermal barriers had a influence on how much surfaced temperature is carried forward to the next power cycle.  I tried different types of thermal coatings and different thicknesses.  The thinnest thermal coatings on the piston crowns caused the least pre-inition problems but the under side showed higher piston crown temperatures than piston that had thicker thermal coatings. 

I do not remember the names of the different thermal coating we tested.  I remember some were gray, some white and some were light pink but all caused pre-ignition.

The best surface treatment we found was to put a highly polished surface on the piston crown.  Thermodynamic studies back this up and show that polished metal surfaces have the lowest emissive powers than dull metal surfaces  The polished surface reflects heat back into the combustion gases less than the thermal barriers but a polished crown will have a cooler surface temperature than a crown that is insulated with a thermal barrier or has a surface texture of a unpolished crown. 

For those that want to delve deeper into the subject, refer to the thermodynamic properties of an insulators, heat transfer and how the surface temperature of an insulator tends to mirror the environment the insulator is exposed to as well as the thermal inertia of that surface vs time.