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Old 11-04-2003, 01:39 AM   #1
RallyOttawa
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Default Quiet down my Borla header... how? Resonator?

I have borla header and Prodrive WRSport exhaust on my 1999 GC8. I want the in-cabin noise to be quieter for the long trips I've been taking.

Would a resonator quiet it down? Would a resonator affect the noise coming from the header?

Should I dynamat my floor/doors/engine bay?

Any help would be greatly appreciated. Thank you!
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Old 11-04-2003, 05:24 AM   #2
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Is there a resonator on the midpipe of that exhaust already?
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Old 11-04-2003, 09:18 AM   #3
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Header wrap will quiet it down some, but it is not particularly durable. I notice a fair difference in noise when I did my header.
A resonator will quiet the overall exhaust down, but won't do much
for noise coming from the engine compartment.


Stu
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Old 11-04-2003, 09:29 AM   #4
MY99 2.5GT
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I'd be willing to bet its not the header thats causing your in cabin droning. Its the muffler. Just for kicks throw the stock muffler back on and see if the exhaust sounds worlds quieter. My setup is pretty loud around town but for long trips I stick the stock muffler back on and enjoy near stock noise levels still with above stock performance.

One thing that will help is to dynamat your trunk area. That is where a lot of vibration and excess noise from the exhaust gets in and resonates. It made a huge difference in my Legacy. Be sure to double layer the area right above muffler.

Resonators don't do much. Its all in the muffler.

Brad
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Old 11-04-2003, 11:10 AM   #5
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I'm a firm believer in resonators to quiet down an exhaust in general. I had an unresonated setup with borla headers, high flow cat, and magnaflow muffler and it was ungodly loud. I had a glasspack installed backwards (as a resonator not a muffler) and it is amazingly quieter.

eric
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Old 11-04-2003, 12:07 PM   #6
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It's not the muffler... I was running just the prodrive muffler and loved the sound... then I decided why not add the header, engine mounts, and tranny mounts. Now the car is just plain loud. I'm converting back the engine mounts (to lose the vibration), but dynamat seems like a good option on the headers.
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Old 11-04-2003, 12:52 PM   #7
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Do resonator with hi flo cat
Thats what i have planned next
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Old 11-05-2003, 03:33 AM   #8
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Quote:
Originally posted by RallyOttawa
It's not the muffler... I was running just the prodrive muffler and loved the sound... then I decided why not add the header, engine mounts, and tranny mounts. Now the car is just plain loud. I'm converting back the engine mounts (to lose the vibration), but dynamat seems like a good option on the headers.
That may be so, but the sound is not coming from the headers themselves. Its coming from the muffler. The headers just change the overall sound of what comes out of the car.

Ive heard dozens of cars now with Borla headers. The volume and droning is dependent on the muffler, the catback piping and whether there is a resonator installed. If you put Borlas on a car with a stock exhaust, the volume does not increase. If you put it on a car without a resonator and muffler that doesnt do much of any resonating either, its loud as bajesus.

But overall, it sounds like you are extremely sensitive to noise. If that is so, doing any sort of NVH or intake/exhaust mods will not be something you would like.
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Old 11-05-2003, 03:54 AM   #9
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maybe a tampon will help?

sorry had to do it, 12 pack of red hook for $9.00= me make fun of people.

Just have a muffler shop weld in a resonator. I found out that summit racing has tons of ways to make your exhaust not quieter for cheap... lots of in-line mufflers/ resonators. the header wrap should help also.
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Old 11-05-2003, 07:28 AM   #10
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I would swap the stock parts back or turn up your radio

Sadly, anything you could do to limit the noise would hinder performance.

The least of which being serious amounts of undercoating/dynomat which wouldnt even make much of a difference.

I might reaccess why you modified the exhaust system and consider losing the horsepower completely even if only for a short time.
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Old 11-05-2003, 05:33 PM   #11
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I have earplugs for long trips.
Taking them out after a few hours,
is like having ears as fresh as little daisys.
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Old 11-06-2003, 03:30 PM   #12
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okay okay..... I will trade my stock muffler for your prodrive....
I'll even spring for shipping...



But for real, what mid pipe do you have on? The stock one? Im assumine not the stock one....dosent it have a small on already on? Also did you put them both (the borla and prodrive) on at the same time? Im curious because Im looking at a similar setup...and I have a 100mi/day commute....
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Old 11-06-2003, 04:22 PM   #13
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I did them at different times... I loved JUST the prodrive. But then the car really felt "perfect"... and we know what that means.. you begin asking yourself "what else can i do to make this car even more perfect".... so i went headers, and mounts at the same time. It was loud, and rough. Nothing like just the Prodrive.

I run the stock midpipe.
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Old 11-06-2003, 04:54 PM   #14
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"I run the stock midpipe."

When researching my stromung CB I remember reading that just the axle back w/ stock midpipe was louder that the full CB.

Just a thought.
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Old 11-06-2003, 04:55 PM   #15
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So I guess no go on the trade huh??

Yea I believe that the stock midpipe is reasonated....I'll look and check...so you may need to try some of the other suggestions.

Thanks for the info on the Prodrive tho! I'm looking for a nice lowl growl/rumble at low end and WOT, but no drone at cruise.
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Old 11-06-2003, 05:33 PM   #16
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The prodrive will give you exactly what you're looking for... but the Borla will introduce drone...
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Old 11-07-2003, 09:55 AM   #17
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Thats funny I have never heard anyone before report in cabin drone with Borla headers. If you think the pleasant low tone burble characteristic of the Borla header is bad try MRTs or Brullens with an Apexi N1 style muffler. Nothing but drone all the time!

Thick dynamat in the trunk really helps. By the way you can't dynamat the header!?

Even if it sounded fine before with your current muffler, now that the headers are at different lengths and allow more flow it is the muffler that needs changed to control drone or tone.

Brad
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Old 11-07-2003, 05:54 PM   #18
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A resonator will make a difference. I had Stainless Works make a 3" overall diameter resonator to splice into my Borla, Stomung high flow cat, Stromung cat-back system. Although the Stromung system for a Legacy already had a resonator, it needed more damping. It was very effective, and I have subsequently toned it down further by modding a WRX STI muffler to fit.

I finally have a great flowing 2.25" system, with a pleasing tone, that is not too loud. See the link below for all kinds of custom exhaust materials:

http://www.stainlessworks.net/Mufflers.htm
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Old 11-07-2003, 06:17 PM   #19
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Cool... thank you for the info.
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Old 11-08-2003, 04:36 PM   #20
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*threadjack*
Quote:
Originally posted by MY99 2.5GT

One thing that will help is to dynamat your trunk area. That is where a lot of vibration and excess noise from the exhaust gets in and resonates. It made a huge difference in my Legacy. Be sure to double layer the area right above muffler.
Brad
how much does the dynamat weigh?
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Old 11-10-2003, 04:06 PM   #21
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dynamat weighs something like 28 pounds for a 72 sq ft roll.
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Old 11-10-2003, 11:24 PM   #22
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thread jack sorta...is there a 'tip' resonator that would fit my stromung that would help kill drone; it doesnt bother me so much, but friends and guests get annoyed in back seat.

(its a single tip stromung; im lookinng for a really easy snap in solution )
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Old 11-12-2003, 05:36 AM   #23
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Quote:
Originally posted by Jejunum
thread jack sorta...is there a 'tip' resonator that would fit my stromung that would help kill drone; it doesnt bother me so much, but friends and guests get annoyed in back seat.

(its a single tip stromung; im lookinng for a really easy snap in solution )

bump!
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Old 11-12-2003, 05:21 PM   #24
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No, there isnt a tip resonator for stromungs.
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Old 11-12-2003, 11:55 PM   #25
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Updating on quieting down of my borlas... after removing the STI engine mounts today, sounds is SIGNIFICANTLY reduced in the cabin. There is no noise at idle in the car, and it really only growls when I get on it. Good stuff all around.

Prodrive axel-back, borla headers = great boxer sound, low tone, not too much noise.
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