One of the ways that you can improve the response in your engine is by adding a lightweight pulley set. Lightweight pullies have less rotational mass when compared to OEM pullies and less rotational mass means that you will have improved engine response for a little bump in both power and torque.
Part #: 2001
This is the Go Fast Bits 2-Piece Underdrive Pulley Kit which includes the alternator and crank pullies. These pullies have been crafted from aircraft grade aluminum materials and will come in an anodized black finish to blend in well with your engine bay, while getting extra protection against rust and corrosion.
This pulley kit will come with a set of serpentine belts to make this kit ready for installation.
Fitment:
2002-2014 WRX
2004-2019 STI
2005-2009 Legacy GT
2004-2013 Forester XT