Isn´t the first time I instaleda lightweight pulley, in my past car Nissan Tsuru 2001 1.6L have an Unorthodox Racing pulley, and dont have any problem, but the pulley came previously balanced, and this is necesary to prevent future damage, I read this in a nissanforum....
I show some pics...
Stock pulley...
I think the holes are made for balancing the OEM pulley
UR Pulley...
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