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This 100mm billet idler pulley is designed to replace the factory idler pulley located directly beneath and to the left of the supercharger pulley. This pulley is approximately 4" in diameter and 1.75" wide at the belt surface.
In CTS-V or ZL1 applications using a smaller than stock supercharger pulley, belt slippage at higher engine speeds can reduce both boost and power. The larger diameter of this pulley serves to increase belt wrap at the supercharger pulley, as well as increase tension on the supercharger belt. This pulley is an easy bolt-on solution to troublesome belt slippage.