snippet from the website:
Victory Product Design's BMW E36 3 Series Underdrive Pulleys are simple in operation and work by reducing the rpm’s on the belt driven engine accessories. With spirited driving, your BMW's accessories are often overdriven, meaning they are being driven with more power than they actually need to operate at their highest efficiency. By driving these accessories slower, hence the term underdrive, more horsepower is directed to drive the wheels, instead of being wasted on BMW accessories which are already running at peak operating efficiency at speed.
While there might be slight variations in power increases from vehicle to vehicle, you will notice that the engine revs up quicker and is more responsive. Typical power gains range from 5-11 hp at the wheels.
The Victory Product Design E46 non-M3 3 series Underdrive Pulley Kit includes the following:
Underdrive Power Steering Pulley
Underdrive Water Pump Pulley
Properly sized Replacement Drive Belt
Easy to follow instructions
Limited Lifetime Manufacturer's Warranty
worthwhile investment or fad?