Consider for a moment the process of just flowing air into the cylinder minus all other engine operating effects. You have to have pressure differential in order for there to be flow. Regardless of turbo or NA, for the sake of discussion consider at TDC the cylinder pressure is equal to the manifold pressure which is equal to the pressure at the throttle blade (WOT case at this point not considering any residual pressure, just pumping air). As the piston moves down the pressure will want to drop in the cylinder, the air flowing in wants to equalize the pressure, how big of a pressure drop you get is based on the restriction of the intake port and runners…. In each of my previous examples, the pressure drop was 1 psi, so regardless of turbo or NA, a 1psi pressure drop will net the same ACFM(actual cubic feet per minute) of air. ACFM is measure of air volume, not air mass. Since the pressure of the turbo motor is higher, the mass of air for 1 ACFM is higher than the NA case, but the volumetric flow(ACFM) we are considering is the same. Since the flow bench is measuring at roughly 1 psi pressure drop, it gives a good representation for both the turbo motor and the NA motor in my simplified example, since it is volume flow that your are looking at. It takes a little while, and little study and by no means do I have it all nailed down.
In reality, the turbo motor will have higher pressure at TDC on the exhaust stroke than the manifold, unless you have a turbo that can run on less back pressure than the compressor produces in boost, and a well designed NA motor will start at a lower pressure at TDC due to scavenging. This is not considered in my simple example. The intent is to show that for the 1 psi pressure drop ACFM flow is the same for both turbo and NA.