PERRIN 02-05 Subaru WRX / 04-06 STI / 93-11 Impreza Lightweight Alternator Pulley - Red

If you're looking to shave a little weight off your Subaru WRX or STI's rotating assembly, this lightweight alternator pulley from Perrin Performance is a solid option. It's designed to replace the stock, heavier alternator pulley on your EJ engine, helping to reduce the overall mass that the engine has to spin. This can lead to a small but noticeable improvement in how quickly the engine revs, especially in the mid-range.

Perrin makes this pulley from aluminum, which is significantly lighter than the factory steel or cast iron pulley. It's then anodized red for a bit of underhood flair. The idea here is simple: less weight spinning means the engine doesn't have to work as hard to get up to speed. While it's not a massive power gain, it's a popular modification for those who like to fine-tune their engine's responsiveness. It fits right onto the stock alternator shaft, making installation pretty straightforward for anyone comfortable working in the engine bay.