MagnaFlow XMOD Series Cat-Back Performance Exhaust System 19547 for the 2011-2021 Subaru WRX offers the premium features MagnaFlow products are known for: lifetime warrantied multi-metal construction dyno-proven performance featuring straight-through mufflers and fast-flowing mandrel bent pipes. Specially engineered interchangeable components equipped with race bred V-Band clamps allow you to easily switch from MagnaFlowâ€s aggressive exhaust note with the xMOD Muffler Module to the wild sounds offered by the xMOD xTreme Deletes. PLEASE NOTE: While xMOD systems are 100% emissions legal the use of xTreme Deletes is recommended for track use only. Check local noise regulations for street legality. Unique to this system the xMOD Series for the WRX is the very first to feature a dual resonator No Drone Technology (NDT) setup. Tuned to passively cancel out two of the different sound frequencies that can create low exasperated drone we are able to maintain the distinctive note of the Boxer motor while drastically improving the in-cabin experience regardless of the systemâ€s configuration. xMOD for the Subaru WRX: get the sound you want when you want it.