Forget all the store bought octane improvers, they're all worthless... NOS, Lucas, 104+ etc they don't work with our cars. They say they raise the octane 7 points, but what that means is it goes from 93 octane to 93.7 octane and in the process coats the internals of your engine. Like was said, do a search on the net or on hear for xylene. Most of those octane boosters are mostly xylene or toulene, and they charge $8 for a 16 oz bottle. Why not buy a gallon of xylene for $8 and raise your octane by a true 7 points, from 93 to 100 octane. xylene is approximately 118 octane.
3 gallons of 93 octane| 3*93=279
1 gallon of 118 octane| 1*118=118
279+118=397
divide that by 4 gallons 397/4=99.25 octane