Acetone does make a noticeable difference. My 98 Blazer resulted in a 15% to 20% increase using a ratio of 5 ounces per 10 gallons of fuel. More is not always better, higher concentration tends to decrease mileage. Be very acurate when measuring, use a glass measuring device. Acetone will attack certain types of plastic and all types of paint and clear coat...you spill, paint is trash! I agree on the O2 sensors, all upstream sensors, (before the converter) directly affect fuel mileage. Oh, and save your money, use a good quality air filter and skip the K&N.