The whistling is created by one of the runners flowing more or less than the other runners around it. You can also get whistling from a poorly ported head where the flow from cylinder to cylinder isn't close to being equal. Unless you want to rework the manifold on a flow bench you will have to live with the whistle.
__________________
Don't bother giving me "rep", I won't return it and I think it is stupid.
Gracie Barra Clearwater
Gyms in Clearwater, St. Pete and Port Richey
pm me if you are interested in trying a free class at any of the gyms.