When I shopped around on my alternator,alot that I saw recomend not to turn them over 6000 rpm with stock ratio pullies in frequent 6000rpm+ applications for best longevity.
I messed up and got a alt with a chrome pully on it,it squeeks upon rapid accel and decell.I also went for the ribbed v-belt and noticed it seemed to jump around alot after 2000 rpm ........almost like it was loose.Stoped the engine and it was plenty tight,possibly a little too tight from what Denny posted.