Maxima Hi-Test is a concentrated octane booster. Hi-Test is an all organic product containing no metal (lead, manganes or phosphorus) compounds. It readily mixes with all fuels. Hi-Test will suppress detonation and pre-ignition by modifying the burn rate and increasing the auto-ignition temperature of the air/fuel mixture. The use of Hi-Test in your Fuel will eliminate “pinging” and “knocking” and the potentially destructive results of them. It will allow for higher compression ratios and therefore more horsepower. For racing or very high compression engines, or very low quality fuel, higher concentrations of Hi-Test may be required.