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I have a Cobb catted downpipe and greddy supreme sp exhaust. It's pretty quiet to me at cruising speed. Absolutely no drone on the highway too. It only get loud when I give it the beans and my EWG opens up...

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So I had the SPT and the drone became outright ridiculous when I added my Spoolinator kit which was catless at the time. I can’t imagine any amount of resonators solving that. The Corsa was way better than that.

No, the issue never was resolved. The vendor who I bought it from was helpful in managing the attempt and got a middle man to provide a replacement piece at cost. I do like the exhaust otherwise. Was a bad weld on one of the tips.


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I have the SPT on a 15+ STI with Killer bee header, stock intake with HKS Funnel, Cobb catted DP and I do not have drone, the sound is deeper.

I amconsidering the SINGLE Q300, weight savings and some hp, but I could not find anyone with one installed. According to Invidia the noise level is 93 db. Any feedbacl would be nice.

BTW everytime I start the STI the alarm of my neighbour's M4 triggers :)
 

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I have the SPT on a 15+ STI with Killer bee header, stock intake with HKS Funnel, Cobb catted DP and I do not have drone, the sound is deeper.

I amconsidering the SINGLE Q300, weight savings and some hp, but I could not find anyone with one installed. According to Invidia the noise level is 93 db. Any feedbacl would be nice.

BTW everytime I start the STI the alarm of my neighbour's M4 triggers :)
why not just get the Cobb catback?? I love my Cobb turbo back on my 17sti.. sounds deep and doesn't drone :)
 

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why not just get the Cobb catback?? I love my Cobb turbo back on my 17sti.. sounds deep and doesn't drone :)

I do not kown where I read it, here o NASIOC, that aftermarket exhaust does not add hp and some of them are heavier than stock. That is the reason why I am more inclined to the Single q300 is lighter and with less bends in the exhaust system. I like the single exit as you can see on my avatar my S2000 has only one exit and was able to pass the smog and the inspection in Spain

I notice that Cobb is the most popular but I do not know if it is beacuse is the best or because the OTS maps.
 

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I do not kown where I read it, here o NASIOC, that aftermarket exhaust does not add hp and some of them are heavier than stock. That is the reason why I am more inclined to the Single q300 is lighter and with less bends in the exhaust system. I like the single exit as you can see on my avatar my S2000 has only one exit and was able to pass the smog and the inspection in Spain

I notice that Cobb is the most popular but I do not know if it is beacuse is the best or because the OTS maps.
another reason i like the quad setup is it looks completely stock, so no trouble with polizia + the cobb quadtip isn't as obnoxiously loud as some of the single exits (tomei, invidia)
 

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The Subaru Performance Exhaust isn't an option for the 2019 with the mid-pipe change. Can't speak to the Q330, just the Cobb which I'm old and like cause there's no drone and it's the quietest. :)

I just bought a 2019 STI today and am considering Subaru Performace Exhaust or an Invidia Q330!Any comments/
 

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Please explain the mid-pipe.I can stiil order the performance exhaust fron their parts cataloque,but not from the factory!Is it worth it?
 

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Please explain the mid-pipe.I can stiil order the performance exhaust fron their parts cataloque,but not from the factory!Is it worth it?
If you order that from the parts catalogue, it will not fit. Subaru changed the midpipe with the RA and into the 2019, hence why you can’t order it from the factory.
 

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Today I used an Apple app to measure the noise inside de car. I know is not the most scientific study but is the noise level that I heard inside de car. The phone placed in the central cupholders next to hand brake
. Here are the details:

STI MY17 with KB ELH, HKS Funnel, Cobb downpipe, STP Exhaust.
Radio off, Aircon off
Tires 265 Bridgestone RE-01


Normal driving was btw 3k and 4k @50 mph. I did some pulls to 6k and when reducing gears was using heal and toe. Top speed during the pulls was 70 mph.

I lost the file, but remember that the highest noise level, using Z frecuency, was 93db. At ilde was 85db.

At the end I got a nice offer to buy the Q300 single Exhaust. One I installed will repeat the test

J
 

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The HKS Legamax Premium and HKS Super Turbo Muffler are the quietest catback exhausts for the 2011+ STI. I've heard everything out there including Corsa, Cobb, ARK, Milltek, Grimmspeed, Maddad and the Q300 to name a few and they are all louder. The HKS systems have a Helmholtz Resonator in the middle for frequency tuning which is the main reason. The Super Turbo Muffler is actually quieter than the Legamax Premium because of the exhaust tips which kinda sucks because they look better. HKS muffler angle and tip arrangement is also perfect! Many other cbe systems have the mufflers & tips sitting in such a way they look as if they are pointing down.
The stock catback is fairly quite when attached to a properly fitted downpipe with HFC like Cobb. The HKS is louder than the stock exhaust when attached to the same downpipe and in all fairness it should be, but barely.
HKS is also releasing an anniversary edition full Titanium Super Turbo Muffler for anyone who wants to spend around $4k. Looks hot though!
 

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Very interesting. It doesn't look like they sell the full catback for the 5 door unfortunately (I know this is a 2015+ thread). Of note, it looks like their midpipe is 65mm which is important to those who feel they need a 3" exhaust setup.


I've been waiting 3 months on my Milltek at this point. RallySport Direct (rather unapologetically) doesn't seem to be able to get their distributor to get in contact with them. Along with the price and the crapshoot of build quality, I'm debating cancelling that order. Maybe I could just have a shop fab me a new 3" mid pipe with a good enough resonator and keep the SPT axleback (along with ELH and catted downpipe)...


Keep the info coming, guys. 95% of aftermarket exhausts are out for me because of noise levels, and many of them wouldn't work anyway because of how they interact with ELH.
 

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Very interesting. It doesn't look like they sell the full catback for the 5 door unfortunately (I know this is a 2015+ thread). Of note, it looks like their midpipe is 65mm which is important to those who feel they need a 3" exhaust setup.


I've been waiting 3 months on my Milltek at this point. RallySport Direct (rather unapologetically) doesn't seem to be able to get their distributor to get in contact with them. Along with the price and the crapshoot of build quality, I'm debating cancelling that order. Maybe I could just have a shop fab me a new 3" mid pipe with a good enough resonator and keep the SPT axleback (along with ELH and catted downpipe)...


Keep the info coming, guys. 95% of aftermarket exhausts are out for me because of noise levels, and many of them wouldn't work anyway because of how they interact with ELH.
The midpipe is 75mm for the 15+, it's the 11-14 that is 65mm. Don't want anyone to get the wrong idea. The 15+ HKS Legamax and STM also fits the 11-14 so the one HKS shows for the 11-14 which is 65mmm isn't needed.
Legamax Premium 31021-BF001 used for 11-19 STI Sedan using 75mm primary/midpipe.
Super Turbo Muffler 31029-AF013 used for 11-19 STI sedan using 75mm primary/midpipe.
 

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I loved the combo of the catless downpipe and a stock catback. I ran it for almost 3 years. It was the perfect sound increase from stock. Catted would have been the same without the smells or the overboosting in cold temps. Highly recommend it, there's really nothing wrong with the stock catbacks. They perform very well until you get into replacing headers or the turbo.
 

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I loved the combo of the catless downpipe and a stock catback. I ran it for almost 3 years. It was the perfect sound increase from stock. Catted would have been the same without the smells or the overboosting in cold temps. Highly recommend it, there's really nothing wrong with the stock catbacks. They perform very well until you get into replacing headers or the turbo.
I agree. Even though the catback is worth some power (not much) on stock turbo it's hardly worth it for the money spent so the stock catback is usually worth keeping till it's the last thing remaining. I always prefer a HFC as I've gotten older otherwise the fumes make me nauseous. A good quality HFC will not restrict any power or spool on the turbo so the only thing it hurts is your wallet.
My only complaint was on the 11-14 sedan was how far inboard the tips were which would eventually lead to carbon buildup on the bumper staining the paint. Glad Subaru fixed that on the 15+ cars. Not sure if that was an issue for the hatch? I can't remember how mine was since I removed the oe catback almost a decade ago.
 

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The midpipe is 75mm for the 15+, it's the 11-14 that is 65mm. Don't want anyone to get the wrong idea. The 15+ HKS Legamax and STM also fits the 11-14 so the one HKS shows for the 11-14 which is 65mmm isn't needed.
Legamax Premium 31021-BF001 used for 11-19 STI Sedan using 75mm primary/midpipe.
Super Turbo Muffler 31029-AF013 used for 11-19 STI sedan using 75mm primary/midpipe.
Oops. Sorry about that. Thanks for clarifying that. I would just stay in the GR section where I belong :lol: except everything except the 15+ forums is pretty much dead.
 

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I've been doing some reading on Helmholtz resonators vs 1/4 wave. Both are after the same goal, but Helmholtz resonators are based on the velocity of exhaust gases and work on the same principle that causes a sound when the wind or your breath crosses the opening of a beer bottle. 1/4 wave resonators (not sure if there is a more specific name for them - it's basically a closed J pipe) focus more on countering the specific sound waves.

If I had a welder (and the ability to use it proficiently), I would give that a shot. You can try to identify the resonant frequency first, then you basically build the pipe a quarter the length of the wavelength of that frequency if I understand correctly (which in most cases seems to be fairly long, ~ 3 feet). A lot of people actually have one pipe welded on, and then instead of it just being a pipe with a cap on the end, they cap it off with a slightly larger pipe and create a slip fitting so they can effectively modify the length of the J pipe within a specified range. Obviously you'd shoot for the length you calculated, but it sounds like tweaking things even a cm or two can make a difference on effectiveness.

Since DIY welding is out of the question and HKS doesn't have an exhaust with Helmholtz resonator for the GR, I don't think adding resonators will yield great bang-for-the-buck, so I'll likely keep after the Milltek.

With that said, thanks again for the info, this has been an educational moment even if I don't put it into use on my car.
 

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Have you tried ECS Tuning Murf? That's where I got mine from and they may have better luck than RSD in getting the exhaust from Milltech.
 

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Interesting fact: STI performance cat back exhaust is still available and is being sold by Subaru in Canada for 2019 STI models. It's available as a dealer option.
The Subaru Performance Exhaust isn't an option for the 2019 with the mid-pipe change. Can't speak to the Q330, just the Cobb which I'm old and like cause there's no drone and it's the quietest. :)
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I've been doing some reading on Helmholtz resonators vs 1/4 wave. Both are after the same goal, but Helmholtz resonators are based on the velocity of exhaust gases and work on the same principle that causes a sound when the wind or your breath crosses the opening of a beer bottle. 1/4 wave resonators (not sure if there is a more specific name for them - it's basically a closed J pipe) focus more on countering the specific sound waves.

If I had a welder (and the ability to use it proficiently), I would give that a shot. You can try to identify the resonant frequency first, then you basically build the pipe a quarter the length of the wavelength of that frequency if I understand correctly (which in most cases seems to be fairly long, ~ 3 feet). A lot of people actually have one pipe welded on, and then instead of it just being a pipe with a cap on the end, they cap it off with a slightly larger pipe and create a slip fitting so they can effectively modify the length of the J pipe within a specified range. Obviously you'd shoot for the length you calculated, but it sounds like tweaking things even a cm or two can make a difference on effectiveness.

Since DIY welding is out of the question and HKS doesn't have an exhaust with Helmholtz resonator for the GR, I don't think adding resonators will yield great bang-for-the-buck, so I'll likely keep after the Milltek.

With that said, thanks again for the info, this has been an educational moment even if I don't put it into use on my car.
HKS makes a Super Turbo Muffler for the hatch but its expensive and has one large tip per side. It looks good from the back but kinda weird from the rear 3/4 angle. I can say it does sound good and it doesn't have a Helmholtz resonator in it. HKS said they were considering making a quad tip version with smaller tips...it would look better IMO.
Super Turbo Muffler:IMPREZA
 
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