Did any of you horsepower calculator guys ever use this

It appears to be similar to other simplified power calculators in that they don’t show combos using heads that aren’t that good as being capable of making good power.
There isn’t even an input for carb size, or exhaust type.

The air flow number is a major driver in these sims in determining the output.

I ran a couple through there....... the predictions were 70-80hp low.
It’s 115hp low on my friends Stocker motor.

I’m sure if I plugged in numbers from a typical SBC with AFR heads and a single plane manifold the numbers would come out pretty close.