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2017-2021 Civic Si Front-Pipe Back Exhaust

2017-2021 Civic Si Front-Pipe Back Exhaust

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A Performance Exhaust System that dares to REDEFINE the Aftermarket. A statement that the same recycled design and mentality is not good enough for 27WON. When we say REDEFINE, this is what we mean.

The most unique performance exhaust for the 10th gen Honda Civic Si. The 27WON design is about performance and exhaust note without compromise. Made for both the FC1 (sedan) and FC3 (coupe) our unique catback combines three resonator styles to create an exhaust system that growls when you mash the throttle but purrs during the drive to work and long road trips.

Click to see our dual round tip version in action.

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The single resonator features two design styles inside. An absorption resonator and expansion chamber resonator. These act to remove low and high frequencies and allow the exhaust gases to pass straight through. Please note, polished finished shown on resonator as example.

The snaked pipes adjacent have very specific task: to eliminate unwanted drone at specific engine RPM ranges. The two pipes each affect a specific RPM window; ~3000rpm and ~4200rpm. We discovered these two RPMs had excessive drone that we wanted to eliminate. The side-branch resonators do not affect power or peak volume output, they only serve to cancel out specific unwanted frequencies that create obnoxious in-cabin drone.

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An amazing amount of work went into the design of this exhaust system. Our initial concepts were functional, but based upon our opinion and then confirmed by the community, lacked a certain aesthetic. We are fortunate to have an industrial designer on our team so we took another crack at it. Our designer and engineers went back and forth until we came up with a concept we could actually manufacture and that is visually stunning.

But we definitely did not do this alone. All along the way...

The Team at 27WON Performance reached out to the CivicX community for inspiration and damn did you guys and gals talk! You even provided your own renderings! Big thanks to iShift_6 on CivicX Forum. Through this collaborative effort, we’ve been able to create a performance exhaust that not only can REDEFINE the Aftermarket but also the process in which aftermarket parts are developed.

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Every 27WON Exhaust System is made from T304 Stainless Steel tubing that is CNC mandrel bent and precision TIG welded for a long lasting and durable performance part.

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We understand that poor fitment during installation is can be a pain, that’s why we have designed our exhaust system to fit and install with zero issues AND does not require the modification of any OEM parts.

Specially designed step nuts were developed for the connection to the front-pipe so you DO NOT have to hammer out the OEM studs for installation like every other system.

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There are absolutely no compromises with the 27WON Performance Exhaust, not even the bolts and nuts. Every exhaust system comes with 100% stainless steel hardware and multi-layer SS gaskets.

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You talked and we listened. After a year on the market we took your feedback and now offer a dual round tip version for those who want a more classic exhaust look. The dual tip system has the same precision crafted performance and is a more budget friendly option.

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Decreased back-pressure is a huge key to enhancing the performance of your engine. We increased the exhaust piping diameter from 50mm up to 63.5mm to increase exhaust flow and power. This results in 58% increase in cross-sectional area to support future power modifications and increase noise output.

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Designed specifically for the 10th generation Si, the 27WON exhaust is the ONLY performance exhaust that truly captures the Civic's style and brings it into the exhaust tip. The dual asymmetrical tips fill the bumper opening completely providing a clean and professional finish. The high gloss polish finish and unique water jet cut logo plate make a clear statement; this is the best you can get for your Honda.

Check out our blogs below to see the community collaboration that went into the design and creation of this Si catback exhaust.

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All 27WON Exhaust systems feature strong 11mm thick 3-bolt flanges for optimal sealing and perfect alignment during installation. Unlike band-clamps or traditional 2 bolt horizontal flanges, the 27WON 3-bolt flanges will not leak over time. Paired with our custom in house designed multi-layer steel gaskets and you get a long lasting worry free system.

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Find out about our approach to this truly unique catback exhaust system. learn more here graphic

Discover our creative design process.

Check out some of our other exhasut tip designs. redefine graphic

See what makes our tips unique. redefine graphic

You voted and we delivered. redefine graphic

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  • Limited Lifetime Warranty
  • Fully personalized after purchase support on all 27WON products
  • Free Shipping in the Continental U.S. and Discounted International Shipping
  • Complete online installation instructions through the Dozuki App: Search “Performance Installs”
  • Install app downloads can be found here Play Store and Itunes

Installing Your Performance Front Pipe Back Exhaust System

Difficulty: 3/5

3/5 Difficulty




Fits perfectly. Looks great and sounds really good. What else can i say.
I love my 27won exhaust. Hands down the best sounding aftermarket exhaust for the si. I had 2 other brands on my car and neither compare to my sick ass 27won exhaust. Just The exhaust is perfect from the design to the welds to the beautiful crisp sound it makes when I tear up the roads.
I installed the entire turbo back system with catted DP over the long weekend. Fitment and instructions are fantastic. sound is phenomenal, plenty of gurgles and a really nice tone. no CEL for me on my 2020 si. while pricey, 100% worth it. this is what the Si should've sounded like from the factory. I'm grateful for the hardworking and thoughtful people of 27won. 10/10
Looks amazing and sounds perfect! The design suites the car perfectly.
Hands down the best sounding full Cat-less exhaust system on the market period. Check out my build log https://www.civicx.com/forum/threads/simonjr-build-thread-2018-si.45950/ for a more in depth review of the setup.
I installed my front pipe and exhaust the other day. Shipping was quick, the packaging was excellent. I'm very impressed so far this thing is like a work or art! The sound with my stock down pipe is louder then stock and a deeper tone. Its not excessive in any way. I paid import, shipping and exchange rate to Canada and I could not be happier! Quality parts and workmanship.
Looking forward to more parts in the future!

Thanks to everyone at 27won for the great work.
Installed as a full system and let me tell you I couldn’t be happier! I’ve never had an aftermarket exhaust before and was anxious to hear it inside and out. Deciding on a Race Catted system I love the deep grumble from such a small engine focusing on sound quality over pure volume. Would recommend any day! Oh yeah and don’t forget the best tips on the market… it just looks like they belong
So I just bought my 27Won full exhaust system for my 2018 Si coupe! I have to say hands down is an amazing set up. I have the catted version and it's a bit quieter then expected. BUT I feel it is a respectable tone that comes out and I am happy! The packaging when sent to me was very well put together and they over all do really good work! I highley recommend 27Won. I have their Turbo and intercooler to still put on but I am sure I will not be disappointed once those are on! Thanks Vince and the team for taking care of me as well when I have any questions!
What's not to love? It's beautiful, it sounds amazing, and it fits like a glove. Worth the wait for this to finally be available for the coupe. Happy customer, great company, great overall experience.

Buy this already.
First time trying out 27won and now I'm a loyal customer. All of the engineering and R&D that go into their products is unmatched and the fact that they show and want input on their design process is incredible. I went with this front pipe back system along with the catless downpipe for my 18' Si and all I can say is it's perfect. Have had it for a couple months and I love hearing it every single day. They tuned out the drone at highway speeds so it's very daily drivable but when you want it to be loud it still screams. The only thing that had me on the fence was the price, but after installing multiple of their products, it's well worth every penny for the quality this company provides.

Thank you 27won for redefining the aftermarket.
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CEL can be illuminated when purchased with a downpipe
2017-2021 Civic SI coupe and Sedan