Exhaust

The exhaust carries gas away from the engine, quietens it and, on modern cars, cleans it through the catalytic converter and particulate filter. This section covers complete systems and the components for building or repairing one:

• silencers and resonators;
• bends, straight pipes and flexible sections;
• V-band clamps, flanges and gaskets;
• Y- and X-pieces and tips;
• catalytic converters, turbo manifolds, headers, downpipes and sensor bungs.

For a bolt-on upgrade, a system made for the car is the simple route, and the Cat-Back Systems and Axle-Back Systems categories list them by model. For a fabricated or modified system, choose the pipe diameter first and keep it consistent, then the material. Stainless steel resists corrosion and lasts; mild steel is easy to cut, bend and weld, which suits a system that is still being developed. V-band clamps let sections come apart quickly, flexible sections stop engine movement cracking the pipework, and weld-on bungs let you add lambda or temperature sensors.

A few things apply to any exhaust work. Hang the system on sound rubber mounts with enough room to move, and use new gaskets at every joint. Changes at the catalytic converter or downpipe usually mean the engine calibration needs checking before the car goes back on the road. The emissions rules for your use need considering too.