Go Fast Bits GFB 08+ WRX/STi / 09+ Forester / 03-09 LGT 3 pc Underdrive/Non-Underdrive Pulley Kit - 2014 $350.00 $315.00 It might be hard to imagine how reducing the mass of a pulley makes a car go faster, but accelerating a heavy factory pulley from say 3000-7000 RPM in a second or two saps a measurable amount of torque. GFB Lightweight Pulleys reduce inertia by up to 85... Add to Cart