A complete exhaust system replaces everything downstream of the catalytic converter. Its main effect is acoustic: less restrictive silencers, a more pronounced low-end tone, and a sharper-sounding rise in revs. As for power, the gain exists but remains modest on a stock engine, because the restriction in a production engine is mainly upstream - in the catalytic converter and downpipe.

The second effect, less often mentioned but more durable, is weight and durability. A stainless steel exhaust does not rust, can still be removed ten years from now, and weighs less than the original aluminized-steel exhaust. On a car you plan to keep, it is the part you only install once.