aFe MACHForce XP 3in 304 SS Cat-Back Dual Mode Exhaust w/ Polished Tips 16-17 Cadillac ATS-V V6-3.6LaFe MACHForce XP 3in 304 SS Cat Back Dual Mode Exhaust w Polished Tips 16 17 Cadillac ATS V V6 3. 6L This cat back exhaust system incorporates factory style NPP dual mode exhaust valves which use the factory exhaust valve motors (not included). The valves help regulate, direct and control the flow of exhaust gases by opening, closing, or partially obstructing passageways depending on throttle position for maximum performance. Dual free flowing