something I've noticed in the stock vs edelbrock head thing is that the edelbrock does seem to burn a little better. in my case a little easier to set the carbs up for a clean burn. I don't know exactly why; maybe the chamber , maybe angle plug, or maybe the way the air exits the intake port? as far as power goes my comparison is between a set of stage V's fast68plymouth did vs 84cc edelbrocks, with just me cleaning the boogers up in the intake ports in the edelbrocks, good quench both times, not a big difference in power between the two heads. the iron heads were easier to set up the rocker gear vs edelbrock using off the shelf parts. the edelbrock had much better retainer to seal clearance for higher lifts. the 88cc edelbrock is for quench dome pistons. they will run with a flat top piston but would work better with quench domes. the edelbrock should give a very noticeable power increase over a stock '452.