They are basically a stock replacement style head but in aluminum, and in out of the box form flow just a little better than stock.

Designed for stock rockers, stock shafts, stock hold downs, stock hardware, etc etc

All that changes, big time, when the head is ported....as the performance of several members' cars will show.

Did you want historic perspective or exactly what kind of info?

I got it from both sides, man! Customer and Marketing.... but "don't get me started" is the first thought that comes to mind LOL.