Duplex stainless-steel exhaust system with 1 × 100 mm outlets on the left and right for Volvo C30 T5 Facelift, type M — TA Technix

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

The second effect, less often highlighted but 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.