the higher the octane the farther advanced your timing can be before detonation.....assuming you're not getting any now check your timing and see where it really is - if you go up in octane you could bump it up 2 degrees or more depending on how close you want to come. pinging really only shows it's ugly head at high rpms ..your fuel map and timing will be very different up there - basing the results there with static timing is about the only way you have to experiment , but beware - detonation is a bad thing.