ROUSH Performance's Resonator Delete Y-Pipe is a quick and affordable way to eliminate your factory resonator to get deep, aggressive and race-inspired sound. Our Y-Pipe increases flow through your 2015-2021 Mustang I4 exhaust system for maximum horsepower and torque. The 2.5-inch Y-Pipe assembly is made from high-grade mandrel-bent 304 stainless steel to ensure maximum flow with less back pressure and long-lasting durability. The system is designed and engineered using OEM vehicle CAD data to ensure perfect fit. **ROUSH Performance recommends checking your local noise ordinance levels prior to purchase. Pair with our axle back kits to take your Mustang to the next level!2015-2021 Mustang 3.7L ROUSH V6 and 2.3L Ecoboost Exhaust Kit (#421837)2015-2021 Mustang ROUSH 2.3L EcoBoost I4 Performance Pac Level 2 (#422069)