if you read the fine print on the label of the octane booster you will find that it does not add a straight 9 clicks of octane
it adds a faction of a percent to something or other i forget exactly .
check the timing
check the plugs /gap
knock is bad
http://www.stanford.edu/~bmoses/knock.html
does it sound like it's knocking ? or pinging ?
i mean is the sensor doing it's job or giving you false positives