Im running 11.9 to 1 on 93 octane pump gas. No detonation. It's all in combustion chamber design. I'm using Edelbrock Victor junior heads and Keith Black flat top pistons in a 393.
http://www.theoldone.com/articles/Th...5FHead%5F1999/
I'm sure this has been hashed out here before but the link above gives a lot of information relative to combustion chamber design in performance vehicles. It works!
h dog