Ported intake gain?

I remember this topic bringing up whether some were flowing the intake 'flange down/backwards' or pushing through it. As in regards to the Intake by itself.

I've done that before, Its not the correct way though. You can see 340's cfm backwards from a vic 340 ootb ...then see it's really choking it to 245cfm bolted on a 270+cfm port.
Gasket match, blend it to the runner, blend the flange/plenum...and 'leave the rest if you can't test'