Citroen Relay Downpipe

Universal 76mm downpipes run R2,999 to R3,500, with better-finished units around R4,950, and vehicle-specific full systems from R6,000 to R13,000 through our network. The gap between those figures is mostly fitment quality — a universal pipe needs fabrication work to fit, and the labour can erase the saving. Tell us the VIN and whether this is a repair or an upgrade, because the right part is different in each case.

A loud blow at idle that hardens under throttle, a whistle as boost climbs, and black soot marking where the gas is escaping — that soot trail is the most reliable way to find the crack on a hoist. Expect P0420 catalyst codes too, because a leak ahead of the front oxygen sensor upsets everything the ECU thinks it knows about the mixture. On the turbocharged cars the cracks nearly always start at the turbo flange weld.

Briefly, and it is worth understanding why not longer. Exhaust gas leaving at that point is at its hottest and is venting straight into the engine bay, near wiring and hoses. The leak also sits ahead of the oxygen sensor, so the ECU sees false air, richens the mixture and can drop the car into limp mode. Meanwhile unburnt fuel is reaching a hot catalyst, which is the fastest way to destroy one. Fix it before it becomes a converter bill.

On a turbocharged car, yes, measurably — a free-flow downpipe reduces back-pressure right where it costs the turbine most, and paired with a remap typically returns 10-15 kW. Two caveats worth stating plainly. Removing the catalyst to gain that is an emissions failure at roadworthy, so the gain has to come from a better-flowing pipe rather than a missing converter. And on a naturally aspirated C2 or an early C3 1.4 or 1.6 there is essentially nothing to gain, because there is no turbine to unload.

Any Citroen with a turbo, which means the THP petrols, the turbocharged 1.2 PureTech in the newer cars, and every HDi and BlueHDi diesel. The naturally aspirated cars — the C2, the early C3 1.4 and 1.6, and the base Xsara — have a conventional front pipe bolted to an exhaust manifold instead, which is a different part with a different failure pattern. Send the VIN and we will confirm which your car has before quoting.