I have used this Octane Booster. It is the best booster I have ever used. If you have a high compression engine (higher then 10.0:1) this is the product for you. It's easy to use and the gains are felt as soon as you add it to the tank. I added 2 tabs to a 17 Gallon tank with 91 Octane pump gas. If you follow the easy directions on the back, this will give you a octane rating of 92.7 almost 93 octane. You can add tabs up to 100 octane. I even had lasting results in a second tank full, even thou I didn't add any more tabs. It's also safe for O2 Sensors & Catalytic Converters, that's important if this is your daily driver (depending on which state or country you live in). The most noticeable difference is in the acceleration from a dead stop. This is a much cheaper alternative to 100 octane gas at Unocal 76 $8.00 a gallon (California).