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Old 09-06-2006, 03:12 PM   #151
shortah
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By the way, the bill wasn't passed in Virginia, I just went and looked at the code. 46.2-1049 still reads the same. With NO changes.
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Old 10-04-2006, 09:06 PM   #152
yayitzian
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just came across this thread again today after two years (the last time I saw it) and it's very much more detailed and complete now. just wanted to say thanks.

i run a helix turboback, with helix up, stock exhaust manifold, but port n polished, as well as pnp'd stock turbo amongst other things and i figure i'd just add 1 or 2db from the closest setup you have listed.

thanks agian.

-ian
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Old 10-10-2006, 05:04 PM   #153
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fwiw, just tested my TBE.

Invidia catless downpipe + Perrin dual tip catback: idle=93dB, WOT=113dB
Not sure what brand meter, but was taken 6ft straight back and level with exhaust.
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Old 10-11-2006, 11:14 AM   #154
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so if i can read properly i would say that the quietest option for a tbe with everything else stock is the stealthback and oval tip?
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Old 10-11-2006, 02:07 PM   #155
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Quote:
Originally Posted by avsmusic1 View Post
so if i can read properly i would say that the quietest option for a tbe with everything else stock is the stealthback and oval tip?
Pretty much. Except it's not really very quiet. Quieter than most, but definitely not quiet.

Quietest TBE would be stealthback + sti muffler.
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Old 10-11-2006, 02:14 PM   #156
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Quote:
Originally Posted by avsmusic1 View Post
so if i can read properly i would say that the quietest option for a tbe with everything else stock is the stealthback and oval tip?
If that's the way you interpret the results then yes. There is some play in these results as the Stealthback+oval tip was on my car and was quiet. There are also other combos that are equally as quiet to the ears like the EVO or others. The numbers just give you a general indication of quiet/medium/loud and from there, you can decide that I prefer the look/reviews/fitment of the XXX vs. the YYY. For example, one of the new quiet ones that I haven't update the chart with yet is the Massiv catback which I now have on my car. It's quiet, but it also has the "JDM angle fitment" to it. Some love it, some hate it, some don't care. The fitment may be a buy or pass for this exhaust even though it's quiet. So if quiet is what you want.....look for a RANGE of quiet exausts, research them, and choose as there are fitment, tip size, piping size, and other issues to decide as there is a big difference between a Prodrive 2 1/4" straight exhaust and the Massiv 2 7/8" angled exhaust (for example).
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Old 10-11-2006, 08:47 PM   #157
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I'll add a little food for thought: When comparing sound levels, a 3dB difference in Lp (sound pressure level) is considered "barely noticeable" subjectively; a 6dB difference is "readily noticeable"; and a 10dB difference is twice/half as loud. So if a stock WRX is 86dB(A) at idle, then you wouldn't be able to tell a difference for any exhaust that was 89dB(A) or lower at idle. At the same time, an exhaust that's 96dB(A) at idle would subjectively be considered "twice as loud". Not set in stone, but certainly an industry accepted reference in acoustics (environmental/building/architectural acoustcs, etc).

Also, something everyone needs to consider is perception. What's quiet to one person may not be quiet to another. Case in point - I had a TurboXS (catted) Stealthback w/Prodrive axleback (oval), considered one of the quietest exhaust systems out there. But to me, it was too loud. Also, as an acoustical consultant in Manhattan, I can't tell you how often I am faced with this very issue. We get calls all the time with people complaining of a "noise" only to find out on-site that the "noise" so faint that most people probably wouldn't even think twice about it. But it's obviously bothering someone. Again, it's the perception of noise.

Keep these things in mind when comparing sound data.
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Old 10-11-2006, 09:39 PM   #158
sajohnson
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Quote:
Originally Posted by Vikingmoose View Post
I'll add a little food for thought: When comparing sound levels, a 3dB difference in Lp (sound pressure level) is considered "barely noticeable" subjectively; a 6dB difference is "readily noticeable"; and a 10dB difference is twice/half as loud. So if a stock WRX is 86dB(A) at idle, then you wouldn't be able to tell a difference for any exhaust that was 89dB(A) or lower at idle. At the same time, an exhaust that's 96dB(A) at idle would subjectively be considered "twice as loud". Not set in stone, but certainly an industry accepted reference in acoustics (environmental/building/architectural acoustcs, etc).

Also, something everyone needs to consider is perception. What's quiet to one person may not be quiet to another. Case in point - I had a TurboXS (catted) Stealthback w/Prodrive axleback (oval), considered one of the quietest exhaust systems out there. But to me, it was too loud. Also, as an acoustical consultant in Manhattan, I can't tell you how often I am faced with this very issue. We get calls all the time with people complaining of a "noise" only to find out on-site that the "noise" so faint that most people probably wouldn't even think twice about it. But it's obviously bothering someone. Again, it's the perception of noise.

Keep these things in mind when comparing sound data.

Very helpful post Vikingmoose, thank you!
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Old 10-12-2006, 06:25 PM   #159
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Quote:
Originally Posted by Vikingmoose View Post
Case in point - I had a TurboXS (catted) Stealthback w/Prodrive axleback (oval), considered one of the quietest exhaust systems out there. But to me, it was too loud.

Hey Justin, I noticed that you said, "had." What do you have now?

Last month, I spent over a week at home recovering from a tonsilectomy. Once I got in my car again, I thought my exhaust (3" catted downpipe, 2.5" rear exhaust pipe, Prodrive axleback) was annoyingly loud. I've since gotten used to it again, but I wouldn't mind something quieter.
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Old 10-12-2006, 07:42 PM   #160
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Still have the catted Stealthback but with an STi axleback. It's nice and quiet but I do miss the boxer rumble. If I could have stock volume AND the boxer rumble I'd be in heaven. The Fujitsubo exhausts look like they are quiet enough according to their published sound data but who knows how loud they really are.
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Old 10-12-2006, 07:45 PM   #161
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Quote:
Originally Posted by Vikingmoose View Post
I'll add a little food for thought: When comparing sound levels, a 3dB difference in Lp (sound pressure level) is considered "barely noticeable" subjectively; a 6dB difference is "readily noticeable"; and a 10dB difference is twice/half as loud. So if a stock WRX is 86dB(A) at idle, then you wouldn't be able to tell a difference for any exhaust that was 89dB(A) or lower at idle. At the same time, an exhaust that's 96dB(A) at idle would subjectively be considered "twice as loud". Not set in stone, but certainly an industry accepted reference in acoustics (environmental/building/architectural acoustcs, etc).

Also, something everyone needs to consider is perception. What's quiet to one person may not be quiet to another. Case in point - I had a TurboXS (catted) Stealthback w/Prodrive axleback (oval), considered one of the quietest exhaust systems out there. But to me, it was too loud. Also, as an acoustical consultant in Manhattan, I can't tell you how often I am faced with this very issue. We get calls all the time with people complaining of a "noise" only to find out on-site that the "noise" so faint that most people probably wouldn't even think twice about it. But it's obviously bothering someone. Again, it's the perception of noise.

Keep these things in mind when comparing sound data.
In addition to what I had said previously, I also want to comment that two exhausts with the same sound level, may sound completely different. This is due to several factors including the spectrum shape -- ie: how loud is something at different frequencies. It is possible to have two exhausts both read 90dBA but sound entirely different because one could be more bassy (louder in the lower frequencies) while the other may be more raspy (louder in higher frequencies).

More food for thought.
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Old 10-12-2006, 08:02 PM   #162
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Quote:
Originally Posted by PossumK View Post
Hey Justin, I noticed that you said, "had." What do you have now?

Last month, I spent over a week at home recovering from a tonsilectomy. Once I got in my car again, I thought my exhaust (3" catted downpipe, 2.5" rear exhaust pipe, Prodrive axleback) was annoyingly loud. I've since gotten used to it again, but I wouldn't mind something quieter.
I'm not VikingMoose, but I ran a catted stealthback for a bit less than a day, then put the stock axleback back on. Now have an sti axleback with the stealthback and life is good. Nice and quiet, and very stealthy once you take off the huge chrome tip and paint the rest black :-)
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Old 11-02-2006, 07:22 PM   #163
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i have been trying to find out how loud the bosal twin tip exhaust is as well as the autospeed exhaust. both would be attached to a Helix bell mouth catless DP
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Old 11-03-2006, 11:17 AM   #164
tmeultraman
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before i got rid of it my buddy club spec III jdm exhaust mated to stock dp rated at 113db...fyi for anyone looking into this exhaust, this was tested at an authorized testing location in cali when i got my mod. exhaust ticket
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Old 11-03-2006, 12:59 PM   #165
WRXDriftR
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can you test an open exhaust cutout at WOT?

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Old 11-04-2006, 06:10 AM   #166
bjonga
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Massachusetts resident,

To replace my stock exhaust what should I get that will not be too loud (80 decibels) and still perform better than stock (2002 wrx). I dont want anything loud and want a little more power.

Thanks.
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Old 11-04-2006, 03:26 PM   #167
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how about an EWG at full throttle? does that count as exhaust?
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Old 11-08-2006, 11:49 PM   #168
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has anybody tested the maddad whisper??
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Old 11-10-2006, 02:19 PM   #169
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Also, something everyone needs to consider is perception. What's quiet to one person may not be quiet to another. Case in point - I had a TurboXS (catted) Stealthback w/Prodrive axleback (oval), considered one of the quietest exhaust systems out there. But to me, it was too loud. Also, as an acoustical consultant in Manhattan, I can't tell you how often I am faced with this very issue. We get calls all the time with people complaining of a "noise" only to find out on-site that the "noise" so faint that most people probably wouldn't even think twice about it. But it's obviously bothering someone. Again, it's the perception of noise.



Keep these things in mind when comparing sound data.[/quote]



A lot of great information here. Vikingmoose is correct about perception of loudness, very subjective. Subaru quotes for their SPT exhuast 80 dB for drive by defined by SAE 1470, and 93 dB for the stationary sound level defined by SAE 1169. I read through a copy of the SAE 1169 to see what the test method was. It specifies the microphone to be 0.5 m (20 inches), 45 degrees away from the exhuast axis, and at least 0.2 m (8 inches) up from the pavement. Measurements are to be at idle and at 3,000 rpm. This is different than the method used by Unabomber, 6 inches away and I assume on axis. The 98 dB shown in the spreadsheet included in the post for the SPT is not the same. Loudness goes down futher away from the source. The spreadsheet does provide a wealth of comparative data, how much louder is one over the another. The magazine link data did not appear to describe any test method, but again that data did provide comparative data on hp increase and relative loudness. BTW louder does not mean higher hp increase according to the magazine's dyno results. Another interesting attribute in the SAE 1169 spec calls out the use of A weighted measurement values. What that means is lower frequency sounds are perceived softer than higher frequency ones at the sound pressure level. So the boxer rumble could be perceived less obstrusive than the Honda killer bee sound.

Here is an example where the SAE spec is used by governement http://www.bernco.gov/upload/images/agenda_items/bcc_2004_11_09/5a.pdf#search='SAE%20J1470'

Here is a link to where a test equipment mfger, Bruel & Kjear, applies it http://www.bksv.com/pdf/pulsecat/vehicle_passby.pdf#search='SAE%20J1470'
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Old 12-13-2006, 04:45 PM   #170
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I am also curious about the MadDad TBE. For me its either MD or Cobb, hoping to get the quieter of the two.

After reading this great thread, I have a feeling a TBE w/ STi UP is going to be a little louder than I want, no matter which brand I use.

I still have to use my car for business ride-withs, and I dont want customers thinking I'm a rice-racer or something....maybe I'm being a little too anal about this-
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Old 12-13-2006, 06:02 PM   #171
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ur the man now dogg
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Old 01-18-2007, 03:02 PM   #172
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Shortah, which bill were you referring to in this comment?

Quote:
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By the way, the bill wasn't passed in Virginia, I just went and looked at the code. 46.2-1049 still reads the same. With NO changes.
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Old 02-12-2007, 03:29 AM   #173
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you said you tested invidia...which one did you test?
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Old 02-12-2007, 07:39 AM   #174
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The regular stainless model Invidia is what I tested, if there are different models now, it's the original one I tested.
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Old 05-21-2007, 01:07 PM   #175
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Hello Unabomber,
First of all a big thanks for this information. Can you clarify for us newbies what the Silencer column in the spreadsheet is? Also, did most of these cars have an aftermarket intake where the intake silencer was removed? It's been reported that these are very loud and I was wondering if this would skew the results.

Thanks,
Springsboy
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