GFB 13+ Subaru BRZ / 13+ Scion FR-S Lightweight Alternator Pulley

This alternator pulley is machined from a single billet of 6061-T6 aluminum, a strong and lightweight material. By significantly reducing the rotating mass on your engine, this part helps your engine rev more freely. Think of it like this: it takes less effort for the engine to spin this lighter pulley compared to the heavier factory one. This means more of the engine's power can go to the wheels, rather than being used just to spin the pulley itself. GFB claims this reduction in rotating inertia can be up to 85%, making the engine feel more lively and responsive, especially when you're accelerating through the RPM range.

The design focuses on improving how quickly the engine responds to throttle inputs. It's a bolt-on part, meaning it's designed to fit directly onto your existing alternator without needing other modifications or engine tuning. The manufacturer states that this pulley will not cause engine damage and that the performance of your driven accessories, like the alternator itself, will not be negatively affected.