Over the years, manufacturers have added grooves, vanes, and bumps in intake manifolds and cylinder heads to fight fuel separation issues associated with fuel being atomized so far from the cylinder itself.
It would be interesting to see what was happening to the air and fuel, while the motor was running, with the throttle blades nearly closed. A high speed camera mounted in the intake maybe?
If there was any separation at all........A grove such as the one being talked about........ "Could" in fact make a difference.......
On the flip side..........You could screw up the manufacturers efforts, and actually cause a fuel separation issue.......Dan