This is GNP's Lightweight Alternator Pulley, it's has been CAD designed, CNC milled, then anodized to protect it and give your engine bay some bling.
All of our pulleys are the same size as the stock one, they are not underdriven. So your stock belts will work.
These Lightweight Alternator pulleys work very well without lightweight crank pulley.
As most lightweight pulleys do, they do not create
horsepower, what they do allow your car to reach a higher RPM or boost sooner and that means is more power to the wheels quicker.
By decreasing the parasitic effects that factory accessory pulleys have on a vehicle's engine. This reduces rotational weight and increases efficiency.
This GNP Lightweight Alternator pulley will fit:
Wrx 2008-2014
Sti 2008-2019the stock alt pulley is 165G and the GNP one is 61G.