Billy Boat Performance Exhaust’s Audi TT 1.8T cat back exhaust is precision crafted using 100% T304 stainless steel. CNC mandrel bent 2.5” 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. B&B uses their bold yet stylish 4” round double wall tips finish off the system for a distinctive look. Installation is a breeze as B&B utilizes all of the factory hangers for mounting. 180hp TT owners can also use this cat back with the addition of the 225hp rear valance. Since no engine management sensors are moved or altered this system is 50 state emissions legal and is backed with their limited LIFETIME warranty.