I don't think you get enough horse power benefit to justify the expense. The factory engineers size the pullys a tad larger than necessary. This ensures that the accessories, and the water pump in particular, spin at the rate needed to function properly under all conditions. Call it a safety margin. Smaller crank pulleys work by taking some of this safety margin away. You may not have a problem. But then again? I like the pulleys that GM Performance offers. They are well made, affordable, and as small as the factory engineers are willing to go. Some (most/all?) of the off shore chrome pulleys are junk and the machined billet jobs can wear faster than steel.