Why would low lift head flow hurt power?

I'm going to devote an entire chapter to Intake Valve Opening (IVO) in my book on The Theory and Application of Racing Cam Design.
I consider the IVO and the EVO to be of equal importance, but EVO occurs first.
However, the most important degree in a camshaft is the degree BEFORE the Intake Valve Opening. If you could measure the cylinder conditions at this point, it would tell you how much exhaust gas is left in the cylinder to be pumped out, and what the residual pressure is. These 2 factors determine what reversion you will have when the intake valve opens, and how badly that will hinder cylinder filling on the intake stroke.
You can demonstrate this easily by getting 2 cams ground with identical intake and exhaust profiles, but on 2 different LSAs, say 106 and 108.
Install each cam in the engine on the identical INTAKE centerline. The only different is in the position of the exhaust cam, the intakes having identical opening and closing numbers.
These cams will demonstrate 2 different power curves, with emphasis at different RPMs. All caused by the effect of more or less reversion on the same intake lobe.
Any cam design that opens late had BETTER open fast, or it will develop insufficient area after TDC, and not fill properly.
I have done it this way since January, 1977, as it seems to deliver good results.......
There is a lot more to be said, but I'll wait for later.

From Harold Brookshire. Sadly Harold is no longer with us and so there is no later......You cant fill the cylinder effectively if the the exhaust residual has somewhere to go and the greater the invitation for it to travel up the intake tract the less the cylinder fill will be.

Jon Kaase Tests Airflow Dynamics With His Finger

Maybe ask @Mattax what all that black stuff is in his intake manifold.

Heres what some one very knowledgable had to say about it:

"That inlet manifold looks to have large area runners, although I'm not familiar with the manifold. If they are large then thats not helping the situation. Large runner areas enable any reversion pulse to miss the incoming fuel charge. Its the mixing of the 2 that causes a collapse of the reversion, its a thermodynamic thing, the heat absorption of the fuel and cold air forces the reversion charge to stop progression and start the flow towards the cylinder slightly earlier than the piston alone would do. So when you have a cam thats opening the intake valve too early for the combustion progression of the cylinder a smaller runner intake can help. But its not fixing the real thing, the real thing is to do things that make the combustion go faster."