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Old 09-27-2017, 01:27 PM   #151
jobber
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Quote:
Originally Posted by jimboyokel View Post
That's basically what the SPT system is, straight through perf core mufflers, albeit with slightly bigger pipes. That being said, I look forward to the video detailing this project.
oh really... if i could find one a SPT catback for under $300 i'd prob try it. but then i'd lose the midpipe resonator i love..
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Old 09-27-2017, 01:30 PM   #152
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Originally Posted by jobber View Post
oh really... if i could find one a SPT catback for under $300 i'd prob try it. but then i'd lose the midpipe resonator i love..
not if you get an SPT catback off of an STI
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Old 09-27-2017, 01:53 PM   #153
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Originally Posted by uofime View Post
not if you get an SPT catback off of an STI
Any idea what the part number is on that? This might be the setup I'm looking for (resonated midpipe with straight-through, no-drone mufflers).
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Old 09-27-2017, 02:05 PM   #154
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question: what rpm is this drone you guys are talking about? i only get a drone around 1.9k
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Old 09-27-2017, 02:09 PM   #155
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not if you get an SPT catback off of an STI
really? the SPT catback is different between the 2015 WRX and 2015 STI?

i found it.

https://parts.subaru.com/p/Subaru_20...441SVA000.html
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Old 09-27-2017, 02:15 PM   #156
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Originally Posted by wgb113 View Post
Any idea what the part number is on that? This might be the setup I'm looking for (resonated midpipe with straight-through, no-drone mufflers).

Kind of difficult to find the number, but found it here(link)
Part Number: D441SVA000

Please note, there is also a VA100 version that is spec'd for the WRX and lacks the resonator
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Old 09-28-2017, 07:28 AM   #157
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Originally Posted by anarekist View Post
question: what rpm is this drone you guys are talking about? i only get a drone around 1.9k
1500-2000 rpm. It seems to be the worst driving around town at 30-40 mph. The CVT doesn't help.
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Old 09-28-2017, 10:37 AM   #158
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Stop screwing around with little dinky bullet resonators. Slap a Vibrant ultra-quiet in there. It will take away some volume, but it will flatten out the "frequency response" (having trouble coming up with the correct terminology so a speaker metaphor seems apt)
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Old 09-28-2017, 10:38 AM   #159
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Quote:
Originally Posted by jobber View Post
oh really... if i could find one a SPT catback for under $300 i'd prob try it. but then i'd lose the midpipe resonator i love..


I got a really nice one off of an STI with the resonator for $350 locally.
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Old 09-28-2017, 10:49 AM   #160
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Originally Posted by playslikepage71 View Post
Stop screwing around with little dinky bullet resonators. Slap a Vibrant ultra-quiet in there. It will take away some volume, but it will flatten out the "frequency response" (having trouble coming up with the correct terminology so a speaker metaphor seems apt)
I hear ya but it seems like they're sized to target a specific frequency range. I guess I could record it from inside the cabin and throw it on a spectrum analyzer to get the frequency of the drone...
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Old 09-28-2017, 10:53 AM   #161
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I hear ya but it seems like they're sized to target a specific frequency range. I guess I could record it from inside the cabin and throw it on a spectrum analyzer to get the frequency of the drone...
That's not really how perf'd tube and packed mufflers work. They will eliminate all frequencies at varying levels and the bigger ones are better at eliminating the lower ones, so it's not far off. The sound waves are just being absorbed by the packing, and the lower frequency waves just have more energy in them and pass through the fibers less times bouncing around in the resonator.

The majority of the drone/rasp takes place in the upper mid-range of frequencies and the large size of the ultra-quiet pulls 99% of that annoyance out.

The other thing I forgot to mention is that cars with stock J-pipes can get away with the bullet style in the STi midpipes. the UQ is more for stage 2+ cars.
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Old 09-28-2017, 01:59 PM   #162
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Quote:
Originally Posted by playslikepage71 View Post
Stop screwing around with little dinky bullet resonators. Slap a Vibrant ultra-quiet in there. It will take away some volume, but it will flatten out the "frequency response" (having trouble coming up with the correct terminology so a speaker metaphor seems apt)
Where though? Its not like a VUQ is really small. I don't think there is anyway you could fit it in the midpipe and still have clearance.
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Old 09-28-2017, 02:08 PM   #163
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Where though? Its not like a VUQ is really small. I don't think there is anyway you could fit it in the midpipe and still have clearance.
There's room. Mine is exactly where the factory STi resonator sits. It's smaller than it looks. It's like a mini muffler. I have a picture...somewhere. I'll try and dig it up.
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Old 09-28-2017, 02:12 PM   #164
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Quote:
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Where though? Its not like a VUQ is really small. I don't think there is anyway you could fit it in the midpipe and still have clearance.
This is pretty common.

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Originally Posted by playslikepage71 View Post
There's room. Mine is exactly where the factory STi resonator sits. It's smaller than it looks. It's like a mini muffler. I have a picture...somewhere. I'll try and dig it up.
I'd like to see the position as well. I'll be welding one in myself.
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Old 09-28-2017, 03:17 PM   #165
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I think it's a combination of needing a resonated midpipe and a better muffler design. It does seem like Subaru designed the stock muffler with sound as a high priority...seems they just forgot to drive the car around after they were done to see how it sounded under normal conditions.
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Old 09-29-2017, 11:35 AM   #166
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I'd like to see the position as well. I'll be welding one in myself.
I'll have to get under the car and take a picture, because I guess I don't have one. \_(ツ)_/

Quote:
Originally Posted by wgb113 View Post
I think it's a combination of needing a resonated midpipe and a better muffler design. It does seem like Subaru designed the stock muffler with sound as a high priority...seems they just forgot to drive the car around after they were done to see how it sounded under normal conditions.
The stock mufflers are really good at reducing the sound without "changing the EQ" as it were. The best example of this is someone with a Jpipe that also has the stock midpipe and muffler deletes. It is a super loud, super raspy, totally Honda sounding fart monster. If you put the stock mufflers on you get that but really really quiet. It's like someone trapped a Honda's ghost inside of a 55 gallon drum. If you add the resonator it changes the whole sound and you can run muffler deletes without it sounding terrible.
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Old 09-29-2017, 11:53 AM   #167
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It's like someone trapped a Honda's ghost inside of a 55 gallon drum.
Dead... Lol.
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Old 09-29-2017, 12:09 PM   #168
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Originally Posted by playslikepage71 View Post
The stock mufflers are really good at reducing the sound without "changing the EQ" as it were. The best example of this is someone with a Jpipe that also has the stock midpipe and muffler deletes. It is a super loud, super raspy, totally Honda sounding fart monster. If you put the stock mufflers on you get that but really really quiet. It's like someone trapped a Honda's ghost inside of a 55 gallon drum. If you add the resonator it changes the whole sound and you can run muffler deletes without it sounding terrible.
Well put.
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Old 04-16-2018, 08:24 PM   #169
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I didn't notice this referenced anywhere else so I will post the link. While researching this mod I came across this other forum post which shows the cut out muffler.

http://www.iwsti.com/forums/2015-sti...r-project.html

My buddy got a WRX as a trade for his STI and will likely be giving me the stock mufflers as it was already fitted with a Nameless muffler delete axleback. I am going to give this a go after watching Jobber/Lasthumansgarage videos.
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Old 04-16-2018, 08:26 PM   #170
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I didn't notice this referenced anywhere else so I will post the link. While researching this mod I came across this other forum post which shows the cut out muffler.

http://www.iwsti.com/forums/2015-sti...r-project.html

My buddy got a WRX as a trade for his STI and will likely be giving me the stock mufflers as it was already fitted with a Nameless muffler delete axleback. I am going to give this a go after watching Jobber/Lasthumansgarage videos.
good luck man.
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Old 04-22-2018, 10:41 PM   #171
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How many people ended up doing the mod the OP did?
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Old 04-23-2018, 11:39 AM   #172
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I'm interested in doing this mod as well. I'm currently on stage 2 bolt ons with E85 flex tune on stock STI midpipe and muffler. I think there's a bit of exhaust restriction at my power levels. I'd rather not go with all full on catback for just an extra 10hp, nor do I want the added noise.

Has anyone actually done a before/after dyno pull with this mod? In theory, this looks like it would flow a lot better. I'm guessing this is very similar to all the other aftermarket catback muffler designs.

In addition, is the stock STI midpipe restricting at my power levels? The 2.5'' diameter appears to be adequate, but it does split into two thinner pipes at the Y section.
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Old 04-23-2018, 11:49 AM   #173
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Originally Posted by ayau View Post
I'm interested in doing this mod as well. I'm currently on stage 2 bolt ons with E85 flex tune on stock STI midpipe and muffler. I think there's a bit of exhaust restriction at my power levels. I'd rather not go with all full on catback for just an extra 10hp, nor do I want the added noise.

Has anyone actually done a before/after dyno pull with this mod? In theory, this looks like it would flow a lot better. I'm guessing this is very similar to all the other aftermarket catback muffler designs.

In addition, is the stock STI midpipe restricting at my power levels? The 2.5'' diameter appears to be adequate, but it does split into two thinner pipes at the Y section.
Just add a nameless midpipe.
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Old 04-23-2018, 02:19 PM   #174
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Just add a nameless midpipe.
I already have the STI midpipe. The restriction appears to be at the mufflers, not the mid pipe. So would removing the baffles be even worth the 1 hour of my time? Based on the images, it would seem like removing those metal plates would free up the exhaust.
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Old 09-15-2019, 12:10 PM   #175
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In addition, is the stock STI midpipe restricting at my power levels? The 2.5'' diameter appears to be adequate, but it does split into two thinner pipes at the Y section.
Yes, I know this thread has been quiet for a while . . . like almost a year longer than we've had our '19 WRX. And yes, the 1500 - 2000 rpm noise level is still there in the 2019's, even on closed throttle, such as when you'd want to be in 3rd gear going downhill on a neighborhood street. Boldface to hammer the point across that you don't have to be 'lugging' the engine for the noise to be present.

Ayau - assuming that a single 2.5" diameter pipe is sufficient for the total exhaust flow, half that flow would only require about 1.75" diameter pipes. A safe choice might be 2 @ 2", just in case flow doesn't split perfectly evenly at the Y.

Actually, I'm wondering if it's the muffler case itself resonating, sort of like a drum head except being the 'barrel' part that's flexing. That's what exhaust flow through the inlet pipe perforations is aimed at . . . And that would excite the air between the muffler and the heat shield and get that vibrating as well.

Has anybody even tried constraining the muffler shape to limit its vibration amplitude?


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