All of the points are in .1 increments. ie. a "5 point gain" makes your fuel 87.5 octane.
People use toluene to raise octane at the track. It seems like that would work for you. I'm sure someone who is more knowledgeable about it will chime in later.
"the truth hurts like a big black cell mate and no vaseline" - BigTDogg (MA)