Kartboy Rear Differential Wedgelock System for 15-21 Subaru WRX/WRX STi

Kartboy Rear Differential Wedgelock System — 2015–2021 Subaru WRX / WRX STI Upgrade traction and cornering precision with the Kartboy Rear Differential Wedgelock System, engineered specifically for 2015–2021 Subaru WRX and WRX STI models. This direct-fit carrier modification converts the factory limited-slip behavior into a firmer, more predictable wedgelock action for improved power transfer and stability under load. Key Features Direct replacement for the OE rear differential carrier—no cutting or welding required. Enhanced traction during acceleration, corner exits, and spirited driving. Durable construction using high-quality components to withstand track and street use. Improved consistency over worn clutch packs—reduces torque steer and axle hop. Professional or experienced DIY install —uses factory hardware and carrier interface. Why Choose Kartboy Kartboy products are designed with performance and reliability in mind. The Wedgelock System offers predictable torque biasing that benefits autocross, track days, and aggressive street driving while maintaining everyday drivability on Subaru platforms. Fitment: 2015, 2016, 2017, 2018, 2019, 2020, 2021 Subaru WRX and WRX STI. Optimize rear-end grip and control with a focused, performance-driven solution from Kartboy.