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I recently went to a 15/50 Vortex sprockets with a DID chain. After buttoning everything up, I took it for a test ride and noticed the whine. I called my local bike shop and they told me that the steel from the chain rubbing against the aluminum sprocket was making the noise. I didn't buy it, and took it to a friend who put it on the laser alignment tool. The stock alignment marks on the swingarm were off, and we got it dead on. The whining noise has dramatically decreased, but is still there slightly (and yes, the countersprocket is oriented correctly). I guess I can live with a little noise for the increase in acceleration