Great comparison Lawnboy01. Thank you. :thumb:
The industry has matured to the point that these comparisons will probably become more frequent. Perhaps we should establish/agree on some test procedures?
1) Bore size
2) Test pressure
3) Port volumes
4) Was the test fixture dimension-ally correct to a block? ie bore centers to dowel pin location? C clamping a head to a universal fixture is not repeatable for Duramax heads. They are very bore/location sensitive based on the relationship of the valve to the cylinder wall.
5) Was there a radiused entrance used on the intake?
6) Was there a pipe or exhaust manifold used on the exhaust?
7) Flow bench make and model.
A tool (flow bench) is only as good as the guy using it. After 35 years in the cylinder head industry, I've seen some pretty "interesting" test procedures.