Several years ago, Muscle Mustangs and Fast Fords began extensive testing on the available heads for the 5.0 Mustangs. The articles began with the August 2003 issue and continued for quite a few issues. The following bench flow data was taken from these articles. The data was all given at 28" of water. Included in these articles were how the heads performed on the dyno, valve sizes, spring rates, compression ratios, combustion chamber sizes, and installation info. The information in the articles was extensive and worth purchasing a back copy if you really want to look into the differences in the heads. I've merely given a base sample of the testing figures as published.