Upgraded APR Stage 2 AWD Controller Software represent the highest level of performance optimization available for Gen 5 Haldex-equipped vehicles equipped with a factory controller. While Stage 1 enhances clutch engagement within the factory hardware's operating range, Stage 2 expands that range by integrating APR's upgraded pressure relief valve assembly. This allows the system to safely command significantly greater clutch pressure during launches and high-load events. This ensures that increased engine output is effectively transferred to the rear axle. The result is stronger launches, faster and more consistent AWD engagement and improved traction during aggressive driving. Despite the increased capability, APR Stage 2 retains full OEM integration and system safeguards, preserving factory drivability during normal operation. Clutch pressure is intelligently reduced after launch to minimize unnecessary drivetrain strain while maintaining performance where it matters most. The software and hardware are engineered together as a cohesive system, delivering meaningful performance gains without compromising reliability or daily usability. For enthusiasts demanding maximum AWD performance from their platform, Stage 2 completes the drivetrain upgrade path confidently putting power to the pavement when it counts. VEHICLE COMPATIBILITY: Designed for VW Golf R Mk7 (2013-2019), Audi RS3 8V (2015-2020), Audi TTS 8S: (2016-2023), Audi TTRS 8S: (2017-2022), VW Golf SportWagen, Alltrack Mk7 / Mk7.5 (MQB), VW Tiguan MK2 (MQB), VW Atlas (MQB), VW Taos (MQB), Audi A3, S3 (MQB), Audi Q3 F3 (MQB), VW Passat / Passat Alltrack B8 (MQB), VW T-roc, Seat Cupra Formentor VZ  REQUIRED UPGRADES & SOFTWARE PAIRING: To ensure proper drivetrain performance, consistency, and durability, the following calibrated software combinations are required. These components are designed to work together as a complete system: Audi RS3 Required: APR ECU + APR TCU + APR AWD Software (all w. Haldex designation) | VW Golf R Required: APR TCU + APR AWD Software (all w. Haldex designation) RECOMMENDED TIRES & PRESSURES: The following tire setups were used to achieve APR's published performance figures. For similar results, we recommend Michelin Pilot Sport 4S tires in the following sizes: Audi RS3: Front: 265/30R19 | 30 PSI & Rear: 245/35R19 @ 32 PSI & Volkswagen Golf R: Front: 235/35R19 @ 38 PSI | Rear: 235/35R19 @ 38 PSI