Surely if you were using it as an Octane Booster for Track use it would be exempt from fuel excise? It certainly couldnt be illegal on the track, could it?
REV210: Did you change the C.A.S? How many degrees, if any?
Toluene Octane Booster sounds good. I was talking about it with a friend of a friend 2 days ago, who is a Petro-Chemical Technician or something and he said you would only need a Cup-full to make a difference, I realise this conflicts with all of your mixture levels mentioned here, maybe he has been sniffing it too much I am glad somebody re-dredged this thread from the ether 10-20% sounds like a good level.
A similar thing happens to my car with BP98, I have tried Synergy a couple of times and the problem is not noticeable... Synergy is further away and more expensive - as you mentioned.
Cheers.