I used a larger idler pulley to keep the tension tight on mine, it feels really tight and i did not datalog any belt slip with it so i may not change anything for now.

i just ran out and looked under the hood and i do see how well your fix would work. i am not sure if i need to swap mine but i grabbed my stock one out of the garage and will take it to the part store today to see if i can find a smaller smooth pulley that will work. if i do i will be sure to post up the part number and price for it.

thanks