Right, the best chemical to use is something called Xylene (This is what Millers Octane booster is based on in very diluted quantities). However, this chemical is very harmful, carsonagenic, and in high concentration will melt rubber, strip paint etc.
Next one down is Toluene or Tolulene (Depending which side of the atlantic you are
) This is used to make Xylenes, but is less harmful and found in a lot of paint thinners with up to 50-60% concentration. Here is the chemical mix for your typical paint thinners:
It has approx 50% Tolulene, and diluted will work well as an octane booster.
Also showing in the mix is Acetone. This is what Ive been using for a few weeks. The least harmful of the three, but also the weakest.
Not only will it boost the octane rating of the fuel, it also atomises the air fuel mix better, slows the burning of the fuel, and increases economy - you can also add acetone to Dervs
So there ya go, Im using pure acetone, in small quantities, and have so far noticed better throttle response, more performance, and increased economy.
However, should you decide to try any thinners, Acetone etc etc, its at your own risk!!!
And should you try thinners make sure they are high in Acetone and Tolulene and have minimal other additives as once diluted it shouldnt harm the engine.