Designed exclusively for the B5 A4 FrontTrak this true cat back exhaust system is a direct bolt-on replacement for the factory system. Precision crafted using 100% T304 stainless steel, their proprietary Purge Resonance Technology or PRT design mufflers and 2.5” CNC mandrel bent tubing provide for a smooth uninterrupted exhaust flow. PRT, which is the latest in resonance control technology from B&B allows for a straight through muffler design for a deep sporty note on hard acceleration while the purge chambers collect and cancel the unwanted resonance at cruising speeds with a nice mild touring tone with no interior resonance. Besides the improved sound the B&B system will also increase both horsepower and torque. For aesthetics B&B choose their twin 3” round double wall tips for a bold yet distinguishing look. Like all their products B&B stands behind the A4 system with their limited LIFETIME warranty.