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Discussion Starter · #1 ·
Hey, so, I originally put a Yonaka exhaust on my EG hatch and was really happy with how it sounded out of the gate with the stock d15 and 4-2-1 crap evay headers that were on the car when I bought it. I added an ASR brace and away bar about 24 hours later and the muffler that came with it was a no go for fitment wise. After beating down the corner down far enough to fit with a sledge hammer and making it fit, I had a muffler shop swap it with a Borla ProXS 14" long oval muffler. It was a bit louder but still tolerable.

Fast forward, flip the engine to a k20z3 + DC2.2 cams + 4-1 headers and you can see where this is going. Just too darn loud.

I see lots and lots of info very clearly supporting 3" exhaust on the k-series platform, and have had enough 3" exhausts on cars to be well aware that they're not quieter than 2.5" exhausts, but generally not louder by a ton. I want my cake and want to eat it too, though, so I'm kinda hoping I can do a kteller 3" pipe setup with a resonator and chambered muffler (turbo style or otherwise) and end up with as good or better flow than I've got now with less sound.

I've searched and searched and not found a ton on the topic, though, nothing semi recent or super possible at least. I know having restrictions like a muffler further down is definitely less of a performance drag than smaller pipe, so it seems like it should work reasonably well. Is anyone actually running such a thing though? I'm obviously not looking for anything near stock sound levels, but if I could get a sound level close to the d15 with headers, a resonator where the cat goes, and a Yonaka or WS2 exhaust fitted which is made of stainless steel and flows as well or better that'd be outstanding.

I know exhausts are highly subjective, and what's quiet to one person may be really loud to another, so hopefully the note on the Yonaka setup (which is well known to be among the quieter EG hatch options) helps.

What I've found so far is:
Dynomax VT - were pretty quiet at first but all fail in a year or so, also they're not made any more.
Magnaflow Chambered mufflers (unknown model and specs) - are pretty tame and sound nice.
ES oval - sound great, good and quiet, but are out of production
Anything with switchable valves... - sorry, not interested. I'd rather just lose a couple/few hp always.

Anyone got any specific models that work well, are in production, are made of stainless steel, and don't have major flaws? I'd love to hear what you've got and how you like it.

--Matt
 

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96 civic HX K24a
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My personal exhaust on a previous build was as follows :
Engine -k24/20
All in fab ram horn 2.5” header
3” piping
18” bottle style resonator , was pretty wide as well
Vibrant street power 3” muffler
Added turndown on the end of the muffler

it was very tolerable at normal driving conditions, couldn’t even tell there was a 3” under the car. After vtec it was a rowdy sounding SOB 100% and in my opinion I had my cake and was definitely eating lol I worked around a bunch of v8 guys and even they couldn’t deny she sang a beautiful song. Hope that helps. I am doing the same setup on my new build currently. Same muffler, 18” resonator and 3” piping butwith an RCREW header this time.
 

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Discussion Starter · #5 ·
Thanks, but I'm definitely looking to go quieter than the Street Power. Noise levels in vtec are kinda the primary problem, TBQH. Definitely will seriously consider the turn down though, based on your recommendation. I've just got 2.5" polished straight pipe as a tip now, so nothing spicy in the looks department, and I don't care to go any more flashy than that anyways.

Forgot to mention... I did actually try a chambered muffler between the Yonaka and the Borla, but I made a bad choice due to lack of proper research and it blew up in my face. The ProXS, even being straight through vs chambered, ended up quite a lot quieter than the Magnaflow XL multi chamber I initially tried. So, definitely no to that particular one. There are just so darn many to try and throwing away $100+ per bad choice gets expensive quickly. 😭

--Matt
 

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Discussion Starter · #7 · (Edited)
Hrm. I just wish I could find known quieter mufflers! While surely cheap junk, the Yonaka muffler had a huge body. The Borla on there is only 4x9.5 oval. There's tons of real estate for a taller muffler under there...but seemingly no aftermarket mufflers to fill it!

The Yonaka muffler was easily 6" tall, and even more could probably fit down there....but I've just got this dinky frame. There's only so much sound reduction that can be accomplished by a perforated core through a glass packed canister of this size.

103140


The biggest I see is only marginally bigger: Vibrant Performance 1103 Vibrant Performance StreetPower Performance Universal Mufflers | Summit Racing

I see taller options from some companies, like the APEXi WS2 universal muffler, but they only seem to come with long tips already on them that make them a no go.

--Matt
 

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Discussion Starter · #8 · (Edited)
Maybe something like this could work...


Hard pressed to find any sort of reviews on this brand/style on a 4-cylinder of any sort, though, which worries me a touch. I'd just grab a Dynomax Super Turbo and call it a day, but the only one they make in stainless is too long to fit a hatchback with a sway bar.


Ideally, Dynomax would make this little guy in more inlet/outlet diameters and a 2" shorter 🤬 Super Turbo™ - Offset / Offset - P/N: 17629

--Matt
 

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Maybe something like this could work...


Hard pressed to find any sort of reviews on this brand/style on a 4-cylinder of any sort, though, which worries me a touch. I'd just grab a Dynomax Super Turbo and call it a day, but the only one they make in stainless is too long to fit a hatchback with a sway bar.

--Matt
That muffler looks to have some nice innards to it, should offer some noise reduction 👍
 

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I've wanted to do a chambered muffler now for a long time. I haven't had the time to really play around with it.
 

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Discussion Starter · #11 · (Edited)
I see a few off-the-shelf options that have the right diameter, but I have some doubts about all of them.

Greddy:
Marketed as 92dB with a turbo, so probably pretty loud. Doesn't look like the muffler would clear a bar based on their pics.

Thermal R&D:
Has no resonator and is marketed for turbo cars, so I'm guessing it's pretty loud. It does seem likely to clear a rear bar, though. A touch pricy, but I'd happily pay it if it ticked all my checkboxes.

Skunk2:
At the end of my list in the looks department. Seems likely to be quite loud.

1230 Performance:
Not sure on the quality, not much word on the sound level, haven't yet been able to get into from them on whether or not it'll clear a bar.

Haven't encountered any other so far, but I'm thinking none of those are it...no matter how much my mind wants to find something I can bolt right up and have work.

--Matt
 

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I can tell you 100% the thermal will be loud without a resonator , and the skunk2 is NOT what you’re looking for 😂 had friends with both setups on various engines and none of them were quiet. The skunk2 exhaust gives me buddyclub spec 2 vibes which is another one I don’t care for. Lol have you looked into doing 2 in-line mufflers such as for a sprint car ? They are tubular style so can blend into the mid pipe, paired with another muffler that may give you the sound dampening you’re looking for
 

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Discussion Starter · #14 ·
Greddy wouldn't confirm or deny that theirs would fit with a bar or how loud it is.

Thermal confirmed that it'd be very loud.

1320 apparently clears a bar. I asked for pics and haven't gotten em yet. Seems like it may even be on the quieter side.

I guess possibly 1 for 4 on off the shelf options.

--Matt
 

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Discussion Starter · #15 ·
K, I think this confirms fitment with a bar...
103198

103199

103200


So that seems like the most "direct fit" possibly. Nice big muffler on the back, hit not so big that it encroaches on suspension. I don't know much about this company, but they do seem to be domestically made by a company in NJ.
 

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I am yet to find a true 3" exhaust that is "quiet." However that is a relative term. What is quiet to me might not be quiet to you. Interior also plays a big part of acceptable noise in the car while driving. Are you looking for an exhaust that is quiet from the outside or inside? If you have to keep it 3" and want it quiet on the inside, I'd suggest adding sound deadening/insulation. Otherwise from the outside, adding a mid muffler/resonator is about the only thing you can do to truly lower the decibels, but like I said, I've yet to hear a true 3" that I'd consider quiet.
 

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Discussion Starter · #17 · (Edited)
Looking for reasonably quiet in and out. I could easily have a conversation inside with the Yonaka setup, and it was low key enough not to draw too much attention.

I'm not averse to getting something off the shelf and adding a resonator. I'd need to measure, but it seems like I may be able to fit a Vibrant Ultra Quiet resonator, or some smaller diameter round resonator, beneath the shift box.

I did hear back on the sound level. They claim it to be pretty tame until you get on it (unqualified claim with no reference point, FWIW).

--Matt
 

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Ah well that makes all the difference. I am going to a 2.5" exhaust from a 3" and will have it back on the dyno next month. Hopefully with negligible power loss between the two.
 
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