The new light pulley only 6 pounds

The original pulley is 15 pounds

2.7 HP is gained from every pound lost off the crank shaft.

the best...! the best...!
Unorthodox lightened under drive crank pulley. Made of lightweight Premium U.S. made 6061-T6 billet aluminum. An average of 5 to 12 HP and 4 to 8 lbs.-ft. on normally aspirated engines and 8 to 16 HP and 8 to 18 lbs.-ft. on forced induction engines. Higher gains are possible. For example, a Nissan 300ZX twin-turbo saw gains as high as 37 HP and 45 lbs.-ft. on the dyno just buy replacing the stock crank pulley with the Ultra S lighted underdrive crank pulley. Power gains are obtained in two ways. First, and most important, is the weight loss. An average of 2.7 HP is gained from every pound lost off the crank shaft. 85% of our gains are from weight loss. The rest of the gains are from underdriving, which accounts for about 15% of the total gains. Maximizing weight loss can be achieved at the crank where most of the horsepower gains are found.