Small block Mopar ProMaxx head testing

I notice most everyone tests the exhaust ports without a pipe and you mentioned the lack of air speed on the exhaust side. Since your car is never run without some sort of exhaust why wouldn't you install a pipe for the test and see what kind of difference that makes? I realize a header would most likely make it impossible to get on the flow bench but a single pipe for the port your testing should be able to be used I'd think. What do you think?