My SCR with brodix fast burn heads is 10.78:1 with .045 quench (quench could be better I know), timing 14*/32*. During very Hot weather I was getting a little run on at shut down. I tried octane booster made by KLOTZ and NOS, both products worked at stopping it so it's not snake
oil. Is it worth it and how much does it increase the fuel octane I can't answer that. I stopped using the octane booster because it leaves the MMT deposits.
I started mixing Toluene in my fuel with a touch of Marvel Mystery
oil, that worked also and the car felt responsive, but it was not cheap at 20.00 a gallon and it's dangerous but I just wanted to see. It burned clean also.
Finally I just decided to buy Sunoco 110 leaded race gas 10.00/gal and mix it at 25%. The car likes it and it works for me. Plus it smells good. Do I really need this- No, I can get away with 93 pump gas but a guy I spoke to who is a race motor builder was in the side business of checking fuel at various gas stations in the past said that the fuel at the pumps is so inconstant that you never know when your getting a bad batch and it is not clean. Take a look at the backs of your intake valves someday after running pump gas for a few years (ugly). The race fuel seems to keep things cleaner and it's just good insurance. I'm not worried about the $5.00/gal I'm probably paying for the mixtures. Well this is my humble opinion based on my experiences. Good Luck.