My understanding is that the idea is to segment the airflow, so that at half throttle or below, the top half of the intake deadheads, and you?ve got a longer cleaner ?port? into the half open carb? and at any other point, this just becomes a restriction. The biggest difference is felt on bikes that came hugely over-carbed like a KTM 125SX (39 PWK on a 125!) or CRF250R. I have doubts that there would be any benefit on a 500.
And I haven't seen one for a 41.