usually the ratio is 40-60
40 hi-octane and 60 petrol.
btw i would like to make one thing clear, hi-octance doesnt enhance the output of an engine, it makes it run smoothly and efficiently..prevents knocking..an engine which is meant to run on 96RON wouldn't put out any extra power if you put 100RON in it, on the other hand, if you put in 96RON into an engine which is meant to run on 100RON, it would knock and would affect the fuel mileage and efficiency, but putting in more RON petrol wont let you ride anymore horses.