ECS Underweight Pulley?
 

Looking at doing my timing belt soon and was browsing the ECS website for the "kit" and noticed they have an Ultimate Kit which includes an underweight pulley (not to be confused with an underdrive pulley). States the pulley is 70% lighter than stock which results in increased horsepower. Since the kit is on sale, I would only be paying an extra $20 bones for the pulley. Question is, has anybody used these before and do they work? Any side effects?

Thanks

[Sorry, wrong group]