Downpipes BMW ALPINA B3 G20 G21 / B4 G26 with Sports Catalysts

Downpipe is a component of a vehicle’s exhaust system that channels exhaust gases from the turbocharger to the rest of the exhaust system. It connects the turbo to the mid-pipe and plays a key role in optimizing exhaust flow. By replacing the restrictive factory catalytic converter, a downpipe allows exhaust gases to flow more freely from the turbocharger. In turbocharged engines, this reduces backpressure, enabling the turbo to spool faster and more efficiently, resulting in increased power output, especially at higher RPMs.

1. Improved Exhaust Flow: A downpipe replaces the restrictive factory catalyst, allowing exhaust gases to flow more freely from the turbocharger. In turbocharged engines, this reduces backpressure, allowing the turbo to spool more quickly and efficiently. The result is an increase in power output, especially at higher RPMs.
2. Reduced Backpressure: Stock OEM catalysts often contain restrictive catalytic converters designed to meet emissions standards, which can hinder performance. Upgraded downpipes, especially "catless" or "high-flow catted" versions, reduce this restriction, allowing the engine to breathe better and operate more efficiently.
3. Boost Gains: By improving exhaust flow, the turbocharger can spool up faster and achieve higher boost levels, translating into greater engine power. The faster the turbo reaches its peak boost, the more quickly the engine can generate additional horsepower and torque.
4. Expected Power Gains: On turbocharged vehicles, including many AUDI, BMW and Mercedes models, downpipes can provide power gains in the range of 20 to 60 horsepower and more when combined with ECU tune. The actual gains depend on the car's engine, other modifications, and whether you use a high-flow catalytic converter or opt for a catless downpipe.
   
   

Downpipe can be very beneficial for your engine, by improving performance, reducing turbo lag, and lowering exhaust gas temperatures. However, it requires careful instalation and a proper ECU tune to avoid issues. If all done correctly, it can be a great upgrade without harming the engine.

A stock catalytic converter has a high cell density (typically around 800/900 cells per square inch), which maximizes emissions reduction but restricts exhaust flow, limiting performance. A 200-cell sports catalytic converter has a lower cell density, allowing for significantly better airflow, increased horsepower. The exact performance gains can vary depending on the vehicle's tune and driving conditions. High quality Stainless Steel construction and special precious metal wash coat delivers consistent emissions reduction, with a significant reduction in size and weight. 

Catless downpipes lack a catalytic converter, allowing for maximum exhaust flow, increased performance, and a louder exhaust note, but they produce more emissions and can trigger a check engine light. Catted downpipes include a high-flow catalytic converter, offering a balance between performance and emissions compliance while producing a slightly quieter exhaust.

All BRONDEX® exhaust products are covered by a 3-year warranty. Our Warranty Policy.