I am shooting the Abowyer Javelina and love the thickness and flight, but they whistle. I contacted the company to see what can be done and they said to put tape over the vents. It kills me that I paid 40.00 for heads that whistle. I shoot a 54# SSR recurve by Jim Belcher. Cabelas carbon arrows with 3 grain per inch tube weights 100 grain brass inserts, 5″ fletchings. Total arrow weight of 600 grains with 25% FOC.
Any head with vents/slots cut in it has the potential to whistle as it goes through the air. If yours whistle, do something to reduce the sharp angle made by the vent. Things like putting tape over the vent, rubbing some chapstick or vaseline on the edge of the vent, or roughing it up with a file or stone are all tricks that have solved the problem.