Exhaust

An engine is an air pump. Everything it takes in must come back out, and every obstacle along the way out costs it work: this is back pressure. A sports exhaust is designed to reduce it - and, incidentally, to finally give the car a voice.

Where to start, depending on your engine

On a turbocharged engine, the first real gain comes from the downpipe: it is the most restrictive point in the entire system, right at the turbine outlet. On a naturally aspirated engine, the manifold is what matters, due to the length and equal sizing of its tubes. The rear section, on the other hand, mainly changes the sound - and that is often what people are looking for first.

Diameter is not a competition

Increasing the cross-section frees up the top end of the rev range, but making it too large reduces low-end torque: the gases lose their speed, and with it the scavenging effect that helps empty the cylinder. A 2 × 76 mm system behind a turbo has nothing in common with the same diameter on a standard naturally aspirated four-cylinder engine. In short: on a stock engine, stay close to the stock cross-section; larger diameters are justified behind a modified engine.

Why stainless steel instead of regular steel

The original exhaust is made of aluminized steel: it rusts through from the inside due to condensation from short trips and is replaced every five to eight years. Stainless steel does not rust, can be welded and polished, and can still be removed ten years later without breaking a clamp. It is the part you only install once.

What to know before ordering

Some of these parts require an ECU remap: without one, the engine retains its original map, the gain does not materialize, and the sensors may put it into safety mode. This is indicated on each relevant product page. Also plan on getting new gaskets and clamps: the original ones cannot be retightened twice.