Invidia N1 Catback Exhaust for 12-15 Civic Si (9th Gen, K24Z7)

Invidia N1 Cat-Back Exhaust - 2012-2015 Honda Civic Si (9th Gen, K24Z7)

The N1 is the exhaust that made Invidia's name, and if you've been around Hondas or Subarus for any length of time you already know what one sounds like. On a 9th gen Si, it replaces everything from the cat back with mandrel-bent SUS304 stainless, which frees up your K24Z7 where the factory exhaust chokes it and gives the car the loud, aggressive note the N1 is famous for. It comes in two pipe sizes and in coupe and sedan versions, so you're picking the setup that matches how you actually drive.

2.75 Inch Or 3 Inch? Here's How To Choose

This is the real decision on this page, and bigger isn't automatically better. Exhaust is about velocity as much as flow, and going too large on a mildly built engine costs you the low and mid-range you use every day.

Go 2.75 inch if your Si is stock or lightly modified. It's the quieter of the two and it makes better low-end and mid-range power because it keeps exhaust velocity up where a stock K24Z7 lives. If you daily the car and don't want to fight highway drone on every road trip, this is your pipe. For most people, it's genuinely the faster choice in real driving.

Go 3 inch if you're making serious power or you just want it loud. The larger diameter flows more at the top end, which matters once you've got a turbo or a heavily built motor asking for it. On a stock car it'll be louder and give up some midrange to get there, so buy it knowing that trade.

Coupe And Sedan Are Not Interchangeable

Check your body style before you order, because this catches people. The coupe and sedan exhausts are routed differently and they do not swap. A coupe system won't fit a sedan and a sedan system won't fit a coupe. Confirm which one you've got, pick the matching pipe size, and you're set.

Built From SUS304 Stainless

The whole system is mandrel-bent SUS304 stainless steel, and both halves of that matter. Mandrel bending keeps the pipe diameter consistent through every bend instead of crushing down and choking flow the way cheaper crush-bent systems do. And SUS304 stainless holds up to road salt and humidity far better than mild steel, so this isn't an exhaust you'll be replacing because it rusted out in a few winters. The flanges are CNC-machined so everything seals tight at the connections, and it wears the burnt tip finish the N1 is known for.

The Silencer Comes With It

Here's something worth knowing, because a lot of places sell this separately. The N1 is a loud exhaust, that's the entire point, but Invidia includes a silencer in the box. Thread it into the tip and it takes the edge off for commutes, early mornings, or anywhere you'd rather not announce yourself. Pull it out when you want the full N1 note back. So you're not choosing between an exhaust you love and one you can live with, you get both in one purchase.

Everything You Need Is In The Box

No sourcing gaskets or hunting down hardware halfway through the install. The system ships complete with all the mounting hardware and gaskets required, plus the silencer. Unbox it, get the car up, and put it on.

Get It Tuned After You Install It

Worth planning for. Dropping backpressure changes how the engine breathes, and your air-fuel ratio will shift with it. A tune after installation is how you actually collect the power the exhaust is giving you rather than leaving it on the table with a calibration that no longer matches the hardware. If you've already got a tuner for the car, mention the exhaust when you book it.

Pick Your Version

Who Should Run This Exhaust

This is for the 9th gen Si owner who wants their car to sound like it means it and to breathe properly at the top of the rev range. Whether you're keeping it mild and daily driving it or building the K24Z7 into something serious, there's a version here sized for it. Pick your body style, pick your pipe size honestly, get it tuned, and go enjoy one of the best-known exhausts in the game.

Fits: 2012-2015 Honda Civic Si coupe and sedan (K24Z7). Type: cat-back exhaust system. Material: mandrel-bent SUS304 stainless steel. Sizes: 2.75" or 3" piping. Finish: burnt tip. Includes: silencer, CNC-machined flanges, and all mounting hardware and gaskets. Important: coupe and sedan systems are not interchangeable. Recommended: retune after installation.