Product Details: Install a GFB light-weight under-drive pulley kit and get better throttle response and more power!

How do they do this?

1. Less weight - GFB's pulleys are manufactured on the latest Multi-Axis CNC machines from the highest grade 6061-T6 aluminium billet, making them immensely lighter than their factory steel counterparts. This lower weight yields a large reuction in the rotating inertia of the belt train, allowing the engine to accelerate faster. The effect is similar to fitting a lightened flywheel and is particularly noticeable in the lower RPM range before the turbo spools up. This is because the power required to accelerate a heavy pulley accounts for a much greater proportion of the available power at low RPM.
2. Under-driving - Additional power increases also come from making the crank pulley smaller, thereby slowing down the accessories and reducing the driven load (particularly at high RPM), without affecting their operation.

Fits:

MY03-current (MY04-current in the U.S.) WRX and STi
    -2001 and 2003 kits include the required shorter belts. 2009 is the same diameter as factory and therefore uses the original belts.

Subaru Liberty/Legacy GT (MY03 onwards)
    -2001, 2201 and 2010 kits include the required shorter belts. 2009 is the same diameter as factory and therefore uses the original belts.