Valve Shrouding Q's

Chevy replaced the closed combustion chamber BBC heads with an open chamber. We just recently experienced the same thing here with a pair of heads we had for eight months. We even destroyed one of our own heads trying to get the others to work in the upper lifts. Finally after hundreds of hours testing it came down to a discussion amongst ourselves, what is different with these compared to the heads we have that flow 20+ cfm more? The combustion chamber. Once we changed that, we found our flow. It was a combustion chamber somewhat like the closed BBC combustion chamber. We were leaving it small in an attempt to keep the compression up. Bad choice. Again I've reinforced my opinion that raising one point of compression isn't that big of a deal. Especially if your goal is pump gas.