Enhance the performance and driving experience of your 2018–2025 Audi S4 with APR’s industry-leading aftermarket parts and tuning solutions. From ECU upgrades and turbo enhancements to exhaust systems and intakes, APR offers precision-engineered components designed to deliver noticeable gains in horsepower, torque, and overall responsiveness. Whether you're looking for daily drivability or track-ready power, APR's performance parts bring out the best in your B9/B9.5 S4 with proven reliability

Transform your vehicle with our Engine Control Unit (ECU) Software Upgrades. We optimize the factory engine management system to take full advantage of the engine's capabilities for large leaps in horsepower and torque, along with added features to make the driving experience more exciting.