The one I used to use was called Moroso (don't know the spelling for sure) and it worked really well. The motor i built had 12:1 compression ratio and the car would ping or accually knock really baddly without it. Pre ignition is the cause for the knocking or pinging.With out the octane booster the fuel wants to ignite before the piston is in proper position and can burn a piston etc. Without rambling on, I hope this helped...