Yes, I understand that cylinder heads are an added variable in the system, and that it would be better to eliminate this variable from the test setup. However, all prior manifold flow tests were done on the cylinder head. For the basis of comparison, this procedure had to be continued. Otherwise, the data wouldn't mean much when comparing it to the data from other flow tests. Flow testing the manifold by itself isn't going to give you much if your intent is to compare it to the other manifolds that have been tested previously.