aFe 49-34068-B MACH Force-Xp 3 IN 304 Stainless Steel Axle-Back Exhaust System BlackaFe 49 34068 B MACH Force Xp 3 IN 304 Stainless Steel Axle Back Exhaust System Black Aggressive Sound: Dual free flowing mufflers are used to absorb high pitch tones producing a powerful sound and unleashing all available horsepower and torque. Exhaust Valve: This axle 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