Duplex stainless-steel exhaust system with 1 × 100 mm outlets on the left and right for Volvo V70 III 1.6-2.5FT, type B — TA Technix

A complete exhaust system replaces everything downstream of the catalytic converter. Its main effect is acoustic: less baffled mufflers, a stronger low-end tone, and a more pronounced rise in revs to the ear. In terms of power, the gain does exist but remains modest on a stock engine, because the restriction in a production engine is mainly upstream - the catalytic converter and downpipe.

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