Invidia N1 Catback Exhaust for 06-11 Civic Si

Invidia N1 Cat-Back Exhaust - 2006-2011 Honda Civic Si (8th Gen, K20Z3)

Want more power and a meaner sound out of your 8th gen Civic Si? The Invidia N1 cat-back exhaust swaps everything from the catalytic converter back for mandrel-bent SUS304 stainless piping. Your factory exhaust is restrictive, and it chokes the K20Z3 right where you want it to breathe up top. The N1 opens that up. You get more midrange and top-end power, plus the louder, more aggressive note the Si always should have had. Invidia builds it in two pipe sizes and in coupe and sedan fitments, so you can match it to exactly how you drive.

Which Size: 2.75" Or 3"?

This is the choice that matters most, so here's the straight version. The 2.75" is the smarter pick for most people. It keeps exhaust velocity up, which means better low-end and midrange power, and it stays quieter with less drone on the highway. If you're daily-driving a stock or mildly built Si and you want real gains you can use every day, that's the one. The 3" goes the other way. It's louder and flows more at the very top, so it makes sense if you're running a turbo, chasing big power, or you just want the most aggressive setup possible. On a stock or lightly modified K20Z3, though, the 2.75" actually makes more usable power because it isn't too big for the engine.

SUS304 Stainless, Mandrel-Bent To Flow

Invidia builds the N1 from SUS304 stainless steel with mandrel bends throughout. Those mandrel bends keep the pipe diameter consistent all the way through each curve, so the gases keep moving instead of stacking up like they do in cheaper crush-bent systems. The SUS304 also shrugs off rust far better than mild steel, so if you deal with winter salt or humid summers, this exhaust isn't rotting out on you in a couple of years. The flanges are CNC-machined for a tight, leak-free seal at every connection, and it's finished off with Invidia's signature burnt tip.

What Comes In The Box

• Invidia N1 cat-back exhaust system
• Mandrel-bent SUS304 stainless steel construction
• CNC-machined flanges
• Burnt tip finish
• All mounting hardware and gaskets included

Pick The Right Version For Your Car

There are four versions, split by body style and pipe size. Order the one that matches your car, because coupe systems don't fit sedans and sedan systems don't fit coupes.

• Coupe 2.75" (HS06HC2GTT): quieter, stronger low and midrange power
• Coupe 3" (HS06HC2STT): louder, more top-end flow
• Sedan 2.75" (HS06HC4GTT): quieter, stronger low and midrange power
• Sedan 3" (HS06HC4STT): louder, more top-end flow

Fitment

This fits the 2006, 2007, 2008, 2009, 2010, and 2011 Honda Civic Si in both coupe and sedan, and it fits the 2008 Civic Mugen Si. All of these run the K20Z3, so it's built around that engine. Just confirm your body style before you order so you grab the matching version.

One Tip After You Install It

If your Si is already running other mods, get it retuned once the N1 is on. A freer-flowing exhaust changes how the engine breathes, and a quick tune makes sure you're actually cashing in the power the exhaust unlocks instead of leaving some on the table.

Fits: 2006-2011 Honda Civic Si coupe and sedan, plus 2008 Civic Mugen Si. Engine: K20Z3. Type: Cat-back exhaust system. Construction: Mandrel-bent SUS304 stainless steel, CNC-machined flanges, burnt tip. Sizes: 2.75" (quieter, more low/mid power) or 3" (louder, more top-end flow). Versions: Coupe 2.75" HS06HC2GTT, Coupe 3" HS06HC2STT, Sedan 2.75" HS06HC4GTT, Sedan 3" HS06HC4STT.