Honda Civic Si (2017–2026) · Cat-back exhaust
Is a Cat-back exhaust Worth It on a Honda Civic Si?
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 2017–2026 Honda Civic Si (10th-gen Si (2017–2020) and 11th-gen Si (2022–2026); not the same kits as Type R), 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 Civic Si 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 Civic Si 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: 10th-gen Si (2017–2020) and 11th-gen Si (2022–2026); not the same kits as Type R.
- Si ≠ Type R. FK7/FC and 11th-gen Si use different intakes, exhausts, and calibrations from FK8/FL5 Type R.
- Keep receipts and stock parts if you may need to return to stock for inspection or sale.
- Search terms that usually work: "2017-2026 Honda Civic Si 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 Honda Civic Si
10th-gen Si (2017–2020) and 11th-gen Si (2022–2026); not the same kits as Type R. Si ≠ Type R. FK7/FC and 11th-gen Si use different intakes, exhausts, and calibrations from FK8/FL5 Type R. 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: Honda Civic Si 2017-2026 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.
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FAQ
Does a cat-back exhaust add horsepower to a Honda Civic Si?
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 Civic Si?
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 Civic Si listing.
Updated 2026-11-04. Costs are typical US ranges, not quotes. Check local laws and your warranty before modifying your car.