Hapco Octane Booster converts pump gasoline into high performance fuel. Provides an efficient knock-free performance in all high compression, naturally aspirated and supercharged engines. Prevents damage due to pre-ignition in race cars, street rods, motorcycles, drag boats and all types of high torque, high load operations. Hapco Octane Booster will normally increase the octane number from 2 to 5 points, dependent upon the base stock of the gasoline used and the amount of Octane Booster used. Legal for most types of racing and street use. Harmless to carburetor and pump gaskets, needles and seats. Safe for use in two and four cycle engines. Does not contain aniline, nitrogen, kerosene, oxygenated compounds or manganese tricarbonyl. For Best Results: Always start with the highest octane gasoline available. Add Hapco Octane Booster directly to fuel tank. For engines under a 10 to 1 compression ratio, add 16 oz. per 10 gallons of gasoline. For engines over a 10 to 1 compression ratio, add 16 oz. per 5 gallons of gasoline. Will not harm oxygen sensor or catalytic converter.