I use Torco race fuels Accelerator fuel additive. I get it from S&W Race Cars in Spring City PA. I get it in 32 oz cans for $20 a can. One can in 10 gallons of premium unleaded is stated as giving you 102 octane. I run it in my Cleveland on the street. It has 11.5 compression with cc 4 barrel heads and an Isky cam with 246 - 252 duration at .050 lift and 106 degree lobe centers. I run 36 degrees total timing with 15 degrees initial. It seems to do the job and it is still cheaper than race fuel here in PA which was 7$ to $8 the last time I checked.