GFB 02-10+ WRX/STI Crank Pulley (Not Under-Drive)

When you're looking to make your Subaru's engine feel more responsive, a lightweight crank pulley is a solid upgrade. This part from Go Fast Bits is made from a single billet of 6061-T6 aluminum, then precision CNC machined. It's designed to reduce the rotating mass of the crankshaft pulley, which can sap torque from the engine, especially during quick RPM changes. By cutting down on this inertia, more of the engine's power can be sent to the wheels, making the engine feel more lively and willing to rev.

This isn't an underdrive pulley, meaning it spins the accessories like the alternator and power steering at the same speed as the factory pulley. This is important because it ensures that accessory performance isn't compromised, and you won't need supporting modifications or special tuning to make it work. The reduction in rotating inertia can be as much as 85%, leading to a noticeable improvement in throttle response and a more eager feel from the engine. It's a bolt-on performance advantage that won't cause engine damage.