If you're having problems finding a ceramic coater, it may be of use to make a contact or two in the local aircraft industry.
If this is impossible, a thermal wrap tape such as Thermotec will do the same job, and is readily available from motorsports suppliers.
It's not stuff I personally would put on a bike, but thermal-wrapping your headers gives a visible hardcore edge that can't quite be matched by any other performance accessory...
It DOES work, but the gain for a 100 to 110 BHP engine will be marginal.
The principle here is that internal combustion engines work best in the absence of spent exhaust gases (the faster you can clear a cylinder of waste products, the more room in there for a fresh batch of combustible mixture).
This is helped by the fact that every time a shot of exhaust leaves a cylinder, a low-pressure pulse follows which helps pull the next exhaust charge along with it. This is also the principle behind linked, tuned headers (as well as the pipe that links the two header pipes on R-series).
The hotter the exhaust charge, the faster it's expansive rate, therefore the quicker it will leave the cylinder, therefore the more vacuum it will help create, therfore the more efficiently it helps clear the cylinders.
Any thermal coating is there to ensure that the heat which makes this effect possible is retained by the exhaust gas, and not dissipated to the outside air.