Ford Focus RS (2016–2018) · Cat-back exhaust
Is a Cat-back exhaust Worth It on a Ford Focus RS?
Short answer · Depends
A cat-back replaces the exhaust from after the catalytic converter(s) back to the tips. It changes sound and can slightly change flow; it does not remove cats. For the 2016–2018 Ford Focus RS (Mk3 Focus RS (2016–2018 US only); related ST (2013–2018) shares some chassis parts but not the RS AWD powertrain), Alone, power gains are usually small. Sound and weight are the main reasons people buy one. Pairing with a tune and other supporting mods is where numbers move more. Typical cost: Typical $500–$1,800. Difficulty: Moderate (jack stands, penetrating oil). A true cat-back keeps the catalytic converters, so emissions testing is usually unaffected—but loud systems can still break local noise rules. This page is general guidance—I am not claiming a personal install on every Focus RS kit listed in search results.
- Typical cost
- Typical $500–$1,800
- Difficulty
- Moderate (jack stands, penetrating oil)
- Time
- 2–4 hours
Worth it if…
- You understand this is primarily about sound/feel more than peak power on a stock tune
- You will verify fitment for your exact Focus RS before buying
- You are willing to install carefully or pay a shop
Skip it if…
- You expect guaranteed dyno numbers from a product page
- You will not confirm generation-specific fitment
- You are about to sell the car and want zero modification risk
Will it fit my car?
- Match the kit to your exact years and generation: Mk3 Focus RS (2016–2018 US only); related ST (2013–2018) shares some chassis parts but not the RS AWD powertrain.
- RS-specific intakes, intercoolers, and tunes; do not assume ST listings fit the RS.
- Keep receipts and stock parts if you may need to return to stock for inspection or sale.
- Search terms that usually work: "2016-2018 Ford Focus RS cat-back exhaust".
What it does
A cat-back replaces the exhaust from after the catalytic converter(s) back to the tips. It changes sound and can slightly change flow; it does not remove cats.
Typical gains (cautious)
Alone, power gains are usually small. Sound and weight are the main reasons people buy one. Pairing with a tune and other supporting mods is where numbers move more.
Fitment notes for the Ford Focus RS
Mk3 Focus RS (2016–2018 US only); related ST (2013–2018) shares some chassis parts but not the RS AWD powertrain. RS-specific intakes, intercoolers, and tunes; do not assume ST listings fit the RS. Always match chassis code / generation.
Install difficulty
Moderate (jack stands, penetrating oil). Plan about 2–4 hours.
Emissions / legal caution
A true cat-back keeps the catalytic converters, so emissions testing is usually unaffected—but loud systems can still break local noise rules.
What to search for
Use: Ford Focus RS 2016-2018 cat-back exhaust. Amazon and eBay links are tagged searches—not invented ASINs.
Buy / parts links
Affiliate links: I may earn a commission at no extra cost to you. Prices change; confirm fitment with the seller. Amazon links use tag 8324894-20; no invented ASINs.
Related on ngooyen
FAQ
Does a cat-back exhaust add horsepower to a Ford Focus RS?
Usually little you can feel on a stock tune alone. Real gains tend to show up with a proper tune and supporting mods.
Is a cat-back exhaust hard to install on a Focus RS?
Moderate (jack stands, penetrating oil). Budget about 2–4 hours.
Will this void my warranty?
In the US a modification alone does not void an entire vehicle warranty, but a dealer can deny a claim for a failure they can show the mod caused. Keep stock parts.
Did you test this exact kit?
Not as a blanket claim for every Focus RS listing.
Updated 2026-11-04. Costs are typical US ranges, not quotes. Check local laws and your warranty before modifying your car.