Hi,
Not too much octane improvement, I think.The problem lies in relative percentage. It takes a pretty large volume of oxidizers to really crank up the octane in a gallon of gas. If, for example, you put a quart of everclear in your gas tank with 10 gallons of supposedly 93 premium, which is pretty close to straight ethanol,you might bump octane 5 points, which is .5 actual octane! WHo! WHo!
Now we have 93.5 octane! Isopropyl alcohol, at several percent strength, is far less efficacious than white lightning,let me tell you!
Well, anyway, you can probably see my point. Large percentages of the stuff that increases fuel octane are required to get the action desired.The same holds true with over the counter additives.It just doesn't make even a very small difference. Run 100 unleaded,or use ALKY injection. Don't mess around.