i have 10.4:1 compression ratio and i have aluminum heads, they say alum. head can get away with an extra point of compression, because they can dissipate the heat qucikly, and i run 92 octane on the street no problem and have a seperate fuel system for the nos and run cam 2 in that cell, so when i spray i get some extra octane and have an msd multistep retard, thats how i did it