I am ordering the unorthadox racing pulleys for my S2K this today. But i have a slight problem. I am dropping my car off this weekend to get my supercharger installed. The vortech blower comes with its own crank pulley so i dont need the unorthadox crank pulley. I talked to the tech support at unorthadox racing this morning and he said you can expect to gain 6 to 10 whp by changing just the crank pulley. If you would like to buy just the crank pulley let me know. We can negotiate a price.