What a downpipe does
On a turbo car the downpipe is the first section of exhaust after the turbo. The factory one is narrow and holds the main catalytic converter, so it is the tightest point in the whole exhaust. A wider downpipe lets the exhaust gas leave the turbo faster: the turbo spools sooner, runs cooler at the same boost, and the tune can ask for more. That's why most Stage 2 files are written around one.
On its own, without a matching tune, a downpipe adds noise and little power, and can set a check-engine light. Always pair it with the Stage 2 file from your tuner.
The three kinds
- No catalyst (catless, "race" or "off-road"). The cheapest and the strongest, and the loudest. It removes the catalytic converter, so it breaks the emissions rules in Israel, the EU, the UK and most US states, and fails inspection. The tune also has to switch off the rear oxygen-sensor fault.
- Sports catalyst (high-flow, 100 or 200 cell). A catalyst with fewer, wider cells than the factory one. It flows almost as well as catless, smells less and keeps a check-engine light away on most tunes, but unless it has type approval it is still not road legal in most countries.
- ECE-approved. A sports catalyst with European type approval and the paperwork that comes with it (for example HJS's ECE downpipes, or Milltek's with an EC-approved cat). It's the only kind you can show an inspector, and it costs two or three times as much.
Cars with a particulate filter
Most European petrol cars from about 2018 have a petrol particulate filter (GPF or OPF) behind the catalyst, sometimes in the downpipe itself. A downpipe that deletes it changes the car's emissions approval. If your car has one, choose a downpipe that keeps the filter; HJS lists separate "with filter" versions for that reason, and they cost more.
Prices on twelve cars
The part alone, before fitting, from the makers' and shops' own pages. Each car links to its guide, where every price links to its source.
| Car | No catalyst | Sports catalyst | ECE-approved |
|---|---|---|---|
| VW Golf GTI Mk5 | $399.99 (CTS) | $599.99 (IE) | — |
| VW Golf GTI Mk6 | — | $599.99 (IE) | £1,111.33 (Milltek, HJS cat) |
| Audi A4 B6 1.8T | $286–$291 (Techtonics) | €795 kit (turbo-parts) | — |
| Hyundai Elantra N | $398 (LAP3) | $898.95–$1,398.95 (cp-e) | — |
| Hyundai Veloster N | CAD 760 (N75) | $787.50, 100-cell (XForce) | — |
| VW Polo GTI Mk6 | — | £983.62 (Milltek) | £1,935.60–£2,497.20 (HJS) |
| Seat Leon Cupra 5F | — | — | £2,503.15 (Milltek); €2,701.90 with filter (HJS) |
| Skoda Octavia RS Mk3 | — | — | €2,136.65; €2,957.15 with filter (HJS) |
| Audi S3 8Y | — | — | €3,334.98 with filter (HJS) |
| Audi TT RS 8S | — | — | €3,510.50; €5,259.80 with filter (HJS) |
| BMW 135i / 335i N54 | from $285 (VRSF) | — | — |
| BMW M2 G87 | — | $3,626 (Fabspeed) | — |
"—" means the guide doesn't list that kind for the car. Prices are in the currency of the shop that lists them.
Before you buy
- Check your tuner's Stage 2 file. Some files are written for a catted downpipe and others for any downpipe. Buy the one your file expects.
- Keep the original downpipe. You may need to refit it for inspection, for a warranty claim or when you sell the car.
- Plan the fitting. On many cars the downpipe sits behind the subframe or next to the gearbox; budget a few hours at a shop and new gaskets and clamps.
- Know the law where you live. In Israel any change to the exhaust needs approval under Regulation 380; see tuning a car in Israel and is a tuned car legal and insured?
Keep reading
- How much does tuning cost? Stage 1, 2 and 3 prices on 12 cars
- Do you need a bigger intercooler?
- Stage 1 vs Stage 2: how much each step adds
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