IW STi Forum banner

Quiet -- stock like sound level -- turbo back exhaust

Exhaust 
78K views 149 replies 47 participants last post by  dlheman 
#1 ·
Hey guys. I have a 2016 sti, and am planning on installing a turbo back exhaust. Ideally I would install a catted DP and keep the cat back stock, as I'm happy with the sound.. But I don't want the restriction of the stock exhaust. I know it will be louder, but I want to keep the noise increase to a minimum, and definitely no drone on the hwy. Recommendations? TY.
 
#106 ·
do any of the older single exit exhaust work/fit (like from the older GR)?

I have come to the conclusion after having a few different exhausts, single always sounds nicer (cleaner tone), especially on ELH.

Something about the dual (y pipe) really messes with the sound.
 
#107 ·
do any of the older single exit exhaust work/fit (like from the older GR)?



I have come to the conclusion after having a few different exhausts, single always sounds nicer (cleaner tone), especially on ELH.



Something about the dual (y pipe) really messes with the sound.

I have the Cobb for my GD and VA. And I have to say it's super quiet with single exit on my GD. The quad tips on my VA even though it's quiet creates enough deep rumble to give me a headache on long trips. Both cars stage 3+


Sent from my iPhone using Tapatalk Pro
 
#108 ·
what I am asking is can one buy a GD exhaust and put it on a VA.

The Cobb from the GD sounds better than dual setup found on the VA, and I was a big fan.

I personally hated the Cobb exhaust on my VA. Way too deep and intruded horribly in the cabin. The Corsa was soooooo much better, even though it was much louder. The amount of complaints from family and friends with my Cobb setup didn't help either.

My favorite exhaust (only made for GD), and really nothing comes close (corsa is the closest) is the Apexi WS2. I really want to put that on my car, which is why I am asking.

I assume the fitment would be all kinds of messed up, but maybe an exhaust shop could get it to work?
 
#109 · (Edited)
The GD stuff will not fit the GV/VA platforms without someone fabricating it to fit. The main reason the GD stuff sounds better is because the acoustics aren't split in two at the axle like the late model cars. A single exit exhaust will always sound better on a EJ than a dual especially when acoustics for daily driving are important. I had several systems on my 06 STI from Fujitsubo, Cobb, and eventually the HKS STM which was my favorite. All these, without question sounded better than my 15 STI does with the HKS Legamax Premium.
The main issue you'll find trying to purchase an single exit for the late model cars is all the systems are made for "racing" which makes them loud/er than preferred. No company I'm aware of makes a touring style muffler single exit exhaust for the GV/VA chassis so anything like you are describing must be custom made.
Also consider the car itself has different acoustics so making an exhaust to mimic the same thing on a GD may not yield the exact results you expect.

Not sure if mentioned in previous posts, but any EJ equipped Subaru with the addition of an EL header will sound quieter due to the pulse frequency being evenly spaced. Maybe this would help if you haven't done it yet.

I wish Fujitsubo didn't step down the primary pipe size to 70mm when they use to make the GD stuff 76mm! If they made their new systems with a 76mm primary they would easily be at the same level as HKS or quieter depending on cbe model compared. They have a quad carbon tipped system system that would look awesome! Akropovic Also would be nice but they said they aren't interested in making exhausts for Japanese cars unless it's the R35 GTR...sad:(. The EvoX system they sell the least numbers of and is what made them decide the Subaru market wasn't worth investing in...Im sure they're right.
 
#111 ·
#112 · (Edited)
well, what I did is bought the Corsa, loved the tone of it, and then I sealed the joint with a solid metal plate (welded in there). It's probably not ideal for flow, but i doubt it's truly hurting.

Subaru-weld-off-muffler — imgbb.com

The only problem is I have noticed is that I ever so slightly hear a metal sound (almost rattle sound) on the runoff (letting off the gas) at some rpms 2-3-- think reflecting off the wall in parking garages. But the tradeoff is so worth it! It's been great and even quieter but still retains that Corsa signature sound, but the Invida looks to be the best fit and is super quiet, although not as cool sounding, but arguably the quietest for our cars.
 
#115 · (Edited)
^^there actually is not much room to add another resonator. I tried, and I kept on bottoming out on it.

What on a GD do you think is the quietest? I have had 6 different ones, and by far the Apexi WS2 was my favorite. Maybe I should just buy the muffler and have a shop fab me a catback?

Seriously, the tone is freaking amazing, but so quiet at all the right frequencies when you were not on it.

I mean, come on, I know it is subjective, but I personally think this is perfect! Wish I could get this sound on my 15+

Apexi Noir 2005 Saab 9-2x Aero - YouTube

and on ELH, it's 10x better than any other setup I have heard. Especially at the low speeds-- it has this neat gargle/growl that almost sounds exotic.

WRX Leaving - YouTube
Bugeye Video Clip - YouTube
 
#116 ·
It's tuff to say on the GD. Aren't too many cars on the market that have as many CBE choices as the GD cars do/did.

I guess the question that comes to my mind is when you say "quietest", are you willing to sacrifice power to keep it quiet? I ask because there are systems that are quiet but the mufflers are either restricted or chambered which will limit flow sacrificing power to achieve lower db levels. I personally don't like this option unless there is no other choice.
The Fujitsubo Legalis R exhaust I had on my GD at one time was chambered, but it was super quiet and by far the quietest exhaust I've ever heard on a GD. I lost 20whp on my setup at the time which was around 430whp with a Cobb CBE that was straight through 3" after the entry flange was modified to 3". The Fujitsubo exhaust was so quiet I couldn't hear the car idle in my house. I kept it for the street and ran the Cobb on the track along with the fact the exhaust was actually several lbs lighter than the Cobb. The stainless was thinner and the flanges were stamped instead of 1/2" thick so what it took away in power I felt was justified for the weight savings, noise reduction and looks. Looked so much better and cleaner than the Cobb!
Fujitsubo Legalis R Cat Back Exhaust - Subaru WRX STI 2004 | 790-63031

This was all before I got the HKS Super Turbo Muffler which was the best GD exhaust I had and have heard. I modified the entry flange again and the muffer is straight through 75mm instead of restricting down like so many Japanese systems do. Loved IT!!!

I've never seen an Apexi WS2 on a GD. Would be curious to see it's anatomy and find if it restricts down anywhere or if the muffler is chambered.
 
#117 ·
I am not willing to sacrafice much power so a stright through design muffler is defintely a must. I am okay with it not 3" on the end.

Here is what I had--https://apexi-usa.com/noir-muffler-2002-2007-subaru-impreza-wrx-sti

I have heard the Legalis and it is super quiet, but has no balls, if you know wha I mean.The Apexi has a tone that is quite amazing, and a lot nicer than the COBB, IMO.

I would probably agree the HKS is one of the best ones. Not as good as the Apexi, but certinly uinque and pleasent, even with ELH.
 
#118 ·
Makes me interested to hear one then. My reservation with the Apexi NOIR is for the money the piping is just steel coated. Regular steel will break down quickly under high heat especially when used on track.
I agree with you on the sound of the Legais R, but for me the unintended benefit was hearing more of my turbo which was nice for a change.
I did however love the sound of the HKS STM. It has a very clean, dry not too deep sound that was nice to listen to on track and for me would be hard to beat with another mass produced system.
 
#122 · (Edited)
I agree, and even better when you weld the Y-pipe, so flow is only from one muffler.

Doing this to any of the catback exhausts makes it better.

The Corsa is just so airy and snarkily sounding, which no one else can replicate. I like that it nearly cuts the super boomy and low frequencies that are annoying.
 
#123 ·
Just looked up the price of the Milltek for the 2015+. Wowww I thought it was bad for the GR :lol:

At any rate, as mentioned I have the GR not the VA, but I did finally get ahold of a Milltek CBE. I'm very happy with it, to me it is sort of what you would expect if you got a performance exhaust from an OEM, sort of how M cars or Infinity cars sound from the factory. Still plenty of sound in my opinion, but not crossing over into noise. Without a doubt quieter than the SPT was stock, and sounds 10,000x better than the SPT did with aftermarket downpipe and ELH. No issues with resonance with the Milltek.

To be honest, I don't find the exhaust note to be hugely changed with the ELH. It definitely sounds different as described above, but it still does not sound like an inline 4 to me or anything like that.

I had a little bit of trouble getting everything aligned but nothing major and I got it bolted up without an assistant. I could do without the polished finish but it's not that bad...
 
#124 · (Edited)
Stock like sound level turbo back exhaust is what I’m currently evaluating. Cobb downpipe and titanium exhaust. 75dB crusing inside the cabin vs 72dB with a stock exhaust. Tone is similar just a little bit louder. The low frequency bass when AVCS kicks in at 3k is just like stock as well. It’s a bit quieter than Q300 when new but without baffles that break down I anticipate Cobb will stay consistent over time. I have no idea why a non resonated titanium exhaust is so tame so there’s room to add a Vibrant resonator or Helmholtz in the midpipe to tame it even more. But any quieter just stay stock.


Sent from my iPhone using Tapatalk
 
#125 ·
I just installed a Cobb catted DP with my already installed AWE Touring CB. It is quite a bit louder now. Cruising is OK, but when accelerating it is noticeably louder than with the stock DP/AWE combo. I really like the unique sound of the AWE, but I don't think my neighbors feel the same now that the volume is clicked up a notch.

I am now starting to consider changing to another cat back to bring the volume back down while retaining the DP. In your testing is the Cobb Ti CB noticeably quieter than the AWE throughout the RPM range?

I have read that Milltek ($$$$) and possibly the Perrin dual tube CB are quieter options, too. Anyone have feedback on them with an aftermarket DP?
 
#129 · (Edited)
Yes I think adding a resonator will help tame it. Issue is we can only fit bullet style next to the drive shaft but fitting one at the DP is a great idea.

Prime Motoring can you anything. I met a customer of theirs last weekend building an iAG stg2 tuff GR STI with Milltek resonated catted DP and catback. He didn’t like the drone caused by Cobb CBE in his hatch. His build is still waiting on some parts so I’m looking forward to hearing it!
 
#132 ·
I picked up a used Invidia Q300 to try out. So far I like it. It is noticeably quieter that the AWE Touring, but I miss the bruble on downshifts.

Not knocking the AWE/T, it is a high quality product. It has a really nice unique, exotic sound that works great with the stock DP. It also has a great burble on downshifts. It just becomes too loud for my taste with the Cobb catted DP installed. If AWE offered a quieter resonator/mid section designed for a DP that would be awesome... Wink, wink...

Does anyone how the Q300 compaires to the Milltek?
 
#133 ·
I hope you continue to like it. I had to take the Q300 off after 10k miles. When the baffles go it gets loud and a little raspy with my current setup. It also has that AVCS drone at 3k especially under load going uphill. Cobb reminds me of the Q300 when it was new but Cobb to me sounds quieter than the Q.
 
#136 ·
Yeah the Cobb titanium is the best compromise among the three. It’s quieter than the Q300 and AWE and after a good break it has a smooth tone. I initially felt it droned on the highway vs AWE but it’s more lower note vs higher note. Volume is less 77-78dB vs 80-81dB so after some time getting used to a bassier note it doesn’t fatigue me after 1 hour.


Sent from my iPhone using Tapatalk
 
#137 ·
@EightTenths Thanks for your feedback (again). I seem to be going though the same steps you went through in finding an exhaust that is the perfect compromise. Do you know the the Cobb SS CBE sounds compared to the Ti version? In your opinion is the Ti version worth the additional $$?
 
#141 ·
I have the Cobb Ti catback on my19. Only put 100 miles on it though so far, but cold starts are loud. My neighbors are complaining about it when I leave at 8am. Once the system warms up, it mellows down. I'm in the SF bay area, and I haven't seen any other STI run it around here. For a catback it sounds amazing, but in Cali it might get the CHP to notice you. ($1100 ticket for modified exhaust) I will say though, It's over 95db when cold, and around 85db when warmed up. Ti takes time to warm up, so keep that in mind. It DOES HAVE LESS DRONE THAN THE STOCK EXHAUST!



Video in my post was a warm start after I already took it for a drive. You will still be noticeable when it's warmed up though.





Stock my19 STI Cobb Titanium exhaust
 
#142 ·
I also had the original Tanabe full Ti medalion catback on my05. Was super loud without the suppressor for being a single exit catback.



On my07, I went with a Maddad whisper turbo-back exhaust. Catted DP with divorced wastegate. This was by far the quietest turbo-back exhaust ever. 0 drone, and it was quieter than the catback i'm running now on my19. GST in Hayward CA pro-tuned was 273whp 293wtq with a pro tune on their mustang dyno.



On my audi s4 (4.2 V8) , I had purchased a Milltek H-pipe non-res catback. It was disappointing because it was too quiet. Swapped that out for a Fast Intentions x-pipe non res and was very happy. Brought the volume up and sounded better being a x-pipe.




Maddad made the quietest tbe IMO.
 
#143 · (Edited)
I think what makes a turbo back loud is because most aftermarket downpipe uses 1 cat instead of 2 cats.

I know this because when I was on stock VF48 turbo; just Corsa catback is eerily quiet inside the car until I give it full throttle - but even then it isn't loud inside the car (but what a sound).

Then I added a 3inch downpipe with a single high flow cat and that thing screams volume.

Later on I converted to VF56 twinscroll turbo and have to get HKS downpipe which has 2 cats like OEM for compliances - and suddenly the Corsa catback becomes less loud, somewhere in between stock downpipe and 3" downpipe with single cat.

The only quiet turboback exhaust I could think of is Miltek and Supersprint (they got an amazing looking manifold too!). European design for European sound, but also very European in price.

But if someone knows a good exhaust shop, maybe make a catback with Vibrant ultra quiet resonator and use something like Apexi WS2 muffler (or other similarly constructed Jazma approved muffler).
 
#144 · (Edited)
I think what makes a turbo back loud is because most aftermarket catback uses 1 cat instead of 2 cats.

I know this because when I was on stock VF48 turbo; just Corsa catback is eerily quiet inside the car until I give it full throttle - but even then it isn't loud inside the car (but what a sound).

Then I added a 3inch downpipe with a single high flow cat and that thing screams volume.

Later on I converted to VF56 twinscroll turbo and have to get HKS downpipe which has 2 cats like OEM for compliances - and suddenly the Corsa catback becomes less loud, somewhere in between stock downpipe and 3" downpipe with single cat.

The only quiet turboback exhaust I could think of is Miltek and Supersprint (they got an amazing looking manifold too!). European design for European sound, but also very European in price.

But if someone knows a good exhaust shop, maybe make a catback with Vibrant ultra quiet resonator and use something like Apexi WS2 muffler (or other similarly constructed Jazma approved muffler).
Milltek is not all that quiet either, especially with ELH. The WS2 muffler is the quietest muffler period. I have heavily considered welding one in place of my Corsa bc the tone is similar, just quiter, and the Corsa is definitely one of the more tolerable exhaust out there for our cars so WS2 muffler would be just right for the daily driven 15+. I had it on my last car and loved it. It was a perfect balance. I have even gone to such great lengths to try and make Apexi build one (using my car as the test model) for a WS2 catback.
 
#148 ·
This is the full Miltek turboback. I am not sure if this uses single or dual high-flow cat (the Miltek downpipe is 2 pieces, so you can select to run the first half catless and the second half with cat, or whichever way you want). But I will assume this is with dual catalyst.




But I also know a 2011 STI with miltek catless (which I just remembered it actually belongs to my friend before he sold it). I think he installed Tomei EL manifold too.


Compare that to my car when it was just using Corsa catback (stock everything else inc intake).
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top