I had the J302 heads when they first came out, which was the first aluminum head offered by Ford (Alan Root designed). Loved the weight, but power didn't seem any different against a well-prepped iron factory head. I'm with Howard though in that later on, I installed some AFR 205s, and they transformed the motor, which validated what was being published about how superior it was to the J302. Perhaps Ford improved these heads over the years, to improve them from the original offering.