Yes, it makes a difference. It effectively cools the air charge thus making it less prone to detonation. As a bonus, it keeps emissions in check by attacking carbon deposits. If you run pump gas, you can add a covalizer to further break down the fuels carbon chains to make it easier to burn. I make my own additives for the fuel but I been busy working on various aspects of using methonal injection. On a N/A motor, I have found it gains more power in the midrange to top end power. The engine responds much more quickly with the addition of methonal. From what I can gather as to chemical data, the isopropyl alcohol in it serves to effectively raise the active compression ratio of the fuel while at the same time, the distilled water absorbs heat which reduces combustion chamber temps to lower the engine's sensitivity to detonation while the water also expands which increases power by helping push the piston down the cylinder with added force during combustion. This process increases exponetionally when used with forced induction. When added after air is compressed, it cools the incoming air charge dramatically while adding "expanding" power.