Billy Boat Performance Exhaust’s A6 cat back exhaust is precision crafted using 100% T304 stainless steel. CNC mandrel bent 2.25” throughout the entire system along with B&B’s proprietary Purge Resonance Technology (PRT) design mufflers this system offers a smooth uninterrupted exhaust flow for increases in both horsepower and torque along with a deep, rich exhaust note. The PRT is simple in design yet unique in theory so you can have a deep sporty note on hard acceleration but still a mild tone while cruising without the unwanted resonance. Since there is no cutout on the rear valance of the car B&B uses their stealth or turn down style tip bold and backs this system with their limited LIFETIME warranty.