OK, different car, different engine, but the Saturn guys at SC Racing took the whole darn belt off for their first dyno run and gained a whopping 3hp. They figured the best they could do was about a 20% underdrive for a whopping gain of .6 hp on something that is probably detrimental to engine life over the long haul. Even if it isn't, it's hardly worth the money.
In their words, "In racing, horsepower talks and marketing bull$hit walks."