Duplex stainless-steel exhaust system with 1 × 100 mm outlets on the left and right for Volvo XC60 T6 AWD, type D — TA Technix

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

The second effect, less often advertised and more long-lasting: 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 need to install once.