I think if it was a full race top end head....................you wouldn't find that Swoosh at the guide.
Something that is designed to idle and full throttle........probably not going to have any kind of air twisting in the port.
The LS has to idle,get good mileage and pass Emissions. Waste some energy to make it swirl so that the fuel stays or helps it to stay in suspension at part throttle.
This is just my opinion.
