You are forgetting that TrickFlow didn't set out with I'm going to copy an Edelbrock head and just cast a head. The exhaust port is a way nicer looking port than any Edelbrock, ProMaxx, Speedmaster, ProComp, or any other copied import. One look at TrickFlow heads close-up will tell you this company cares about what they send out the door. (unlike Edelbrock CRAP) TrickFlow could have flow tested their head on a 4.100 bore adapter but they didn't. They instead tested on a 4.000 bore test fixture. I don't personally know Brian at IMM engines in California but he tested on a 4.030 fixture and got slightly higher numbers than TrickFlow did. We are very lucky to have TrickFlow making Mopar products and I for one can't wait to see their next Mopar project.