Gilmer pulleys

My understanding is the belt teeth & the pulley teeth have to be contoured. If you look closely at some, the teeth are at right angles. This causes a sharp contact point as the belt spins, resulting in the noise & fast wear of the belt. Think of them as saw teeth interlocking & you'll get the idea. Some manufacturers, Cragar was one I think, contoured the belts to increase longevity. leaving the pulley side of it up to the end-user.
I suppose you could contour the pulley teeth yourself & go look for a proper belt. Or simply ask the manufacturer if he's done it already.