unfortunately I am guessing but I don't think it is as high as 9 to 1. I haven't been involved with this car for a few years, the motor only has about 2 thousand miles in the last 12 years. I am going to check the 4x heads and see how big the chambers are supposed to be. What I really want to accomplish is for it to sound like it has a radical cam without actually having it thus the specs mentioned