Secondary downpipes for the BMW M5 G90 Sedan and M5 G99 Touring 4.4i V8 S68 are performance parts designed to replace only the secondary catalytic converters in the exhaust system. They do not affect the primary catalytic converters near the turbochargers, ensuring a more straightforward upgrade. Complete M5 G90 / G99 Downpipes System (Primary and Secondary Downpipes) is available also. Benefits of BRONDEX® Secondary Downpipes: No ECU Tune Required (Plug and Play):BRONDEX® M5 G90 G99 Secondary Downpipes are not require an ECU tune, since they don’t trigger a Check Engine Light (CEL). Better Sound:Upgrading to the BRONDEX® M5 G90 G99 Secondary Downpipes results in a deeper, more aggressive exhaust note. Improved Exhaust Flow:Replacing secondary original catalytic converters can reduce backpressure, leading to better performance.Enhanced turbo efficiency and faster spool times. Compatibility with Stock or Aftermarket Systems:BRONDEX® M5 G90 Secondary Downpipes can be paired with the stock exhaust system or a full aftermarket exhaust setup. Materials: BRONDEX® M5 G90 G99 Downpipes are made from 304 Stainless Steel for durability and corrosion resistance. Made in Europe. 3 years warranty.