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BMW 3-Series and 4-Series Forum (F30 / F32) | F30POST > Technical Forums > N55 Turbo Engine / Drivetrain / Exhaust Modifications > Stock F30 335i Axle Back Exhaust Muffler Modification and Dissection
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      03-22-2014, 02:15 AM   #89
EB_F30
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TurboM, I am curious what tips those are too. Is it just the picture or are they different bigger tips?
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      03-22-2014, 06:25 AM   #90
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Thanks! Yeah, Im not paying that...I'll be on the look out.
Look on eBay. You can probably get one for about $75 shipped.

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      03-22-2014, 06:27 AM   #91
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TurboM, I am curious what tips those are too. Is it just the picture or are they different bigger tips?
They're the same factory 335 tips in both videos, must be the lighting.
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      03-22-2014, 08:36 AM   #92
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They're the same factory 335 tips in both videos, must be the lighting.
Ah I see. Yeah they look much bigger in the 1st Video.
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      03-23-2014, 05:57 AM   #93
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Did any of you close all holes in both chambers 1 & 3 ?
Thank you for all the info

/ Krelle
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      03-23-2014, 07:55 AM   #94
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Did any of you close all holes in both chambers 1 & 3 ?
Thank you for all the info

/ Krelle
That's exactly what I did.
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      03-23-2014, 09:02 AM   #95
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Tanks TurboM,

I'll try and copy that and plug the second hole into the Helmholz chamber as well.
I have easy access to some gear and the plug can easily be removed again. This is only a test as my mind is 60-40 against getting a positive result. We'll see when I get to it.
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      03-23-2014, 09:18 AM   #96
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Tanks TurboM,

I'll try and copy that and plug the second hole into the Helmholz chamber as well.
I have easy access to some gear and the plug can easily be removed again. This is only a test as my mind is 60-40 against getting a positive result. We'll see when I get to it.
/Krelle
I don't think there will be any surprises as to what it will sound like if you completely plug everything up in side the muffler. You're basically just doing a muffler delete with the canister still in place. Not sure I would bother if I were you, just my $.02...
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      03-23-2014, 10:21 AM   #97
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you might be right, but I'm corious to see what happens and if it has any effect.
For sure I will not accept any drone like when deleting it.
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      03-23-2014, 07:33 PM   #98
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Quote:
Originally Posted by Krelle
Did any of you close all holes in both chambers 1 & 3 ?
Thank you for all the info

/ Krelle
Yes that's what I did. They were all welded shut.
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      03-23-2014, 07:35 PM   #99
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Quote:
Originally Posted by TurboM
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Originally Posted by Krelle View Post
Tanks TurboM,

I'll try and copy that and plug the second hole into the Helmholz chamber as well.
I have easy access to some gear and the plug can easily be removed again. This is only a test as my mind is 60-40 against getting a positive result. We'll see when I get to it.
/Krelle
I don't think there will be any surprises as to what it will sound like if you completely plug everything up in side the muffler. You're basically just doing a muffler delete with the canister still in place. Not sure I would bother if I were you, just my $.02...
Yep I agree, I'd just weld the small perforated tubes as the result is already proven. It may be a tad bit louder with that second hole plugged up but not sure. I mean if he does it it would be great to se or hear what it sounds like. Keep us posted.
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      03-25-2014, 02:13 AM   #100
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I've been really interested in this type of mod since I saw a thread where M3's were having it done.
What I'm not quite clear on is how sealing up all the holes in the muffler produces less drone and a different sound than straight piping.
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      03-25-2014, 03:03 AM   #101
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Quote:
Originally Posted by twelve535i
I've been really interested in this type of mod since I saw a thread where M3's were having it done.
What I'm not quite clear on is how sealing up all the holes in the muffler produces less drone and a different sound than straight piping.
Because the Helmholtz chamber is still in tact.
It's louder but not to the point where it will emit unbearable drone.
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      03-25-2014, 07:37 AM   #102
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and more importantly (for me) the exhaust note is almost inaudible while cruising. It does get much louder once you pass about 50% throttle. This is definitely not the case with a straight pipe.
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      03-25-2014, 01:58 PM   #103
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Originally Posted by TurboM
and more importantly (for me) the exhaust note is almost inaudible while cruising. It does get much louder once you pass about 50% throttle. This is definitely not the case with a straight pipe.
Spot on.
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      03-25-2014, 02:53 PM   #104
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cool to see something like this ! always thought the E9x M muffler mod sounded great!
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      03-25-2014, 03:47 PM   #105
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cool to see something like this ! always thought the E9x M muffler mod sounded great!
Yes it's where I got my idea initially. So I was very optimistic it would work.

I believe the guys that were doing it on e9x M3 were from Canada. They charged $400 plus your muffler as a core. For the sound it's a pretty good bargain, especially with how much car backs cost now days.
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      03-25-2014, 04:18 PM   #106
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Because the Helmholtz chamber is still in tact.
It's louder but not to the point where it will emit unbearable drone.
What confused me at first was the fact that the tubing in chamber 2 has no holes, so I didn't see how that could drown out any noise.
Now that I look at the picture again, it appears that there is an additional pipe the runs from chamber 1 into 2 that you have no touched. Is that correct?
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      03-25-2014, 04:53 PM   #107
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So how are you going to spot weld on the underside?

Wouldn't having a Meineke guy with tubing make a straight through tube design be cheaper? that's essentially what's being done...no?
In chamber 3 yes that would be the way to go, just cut and replace with a tube and weld it back.

The difficult part would be re fabricating the section in chamber 1. It's not round, it's very much oval. Not saying its not possible, but I doubt it be cheaper then just welding each hole.

The underside plan is to open the muffler even further with my angle grinder so I have access to the underside.

I'm not saying this is going to successful but if I close off the perforated tube there will be a change in the exhaust note. I'm not even sure if it will be a good sound, it may be the most annoying thing we ever hear....but we'll all find out soon
Just wrap it in heat shield and safety wire them down. Thats what i did on mine.
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      03-25-2014, 05:20 PM   #108
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Quote:
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Because the Helmholtz chamber is still in tact.
It's louder but not to the point where it will emit unbearable drone.
What confused me at first was the fact that the tubing in chamber 2 has no holes, so I didn't see how that could drown out any noise.
Now that I look at the picture again, it appears that there is an additional pipe the runs from chamber 1 into 2 that you have no touched. Is that correct?
Yes that is 100% correct. There is a smaller tube leading into the Helmholtz chamber that still slows some of the sound to drown out. This is naturally designed by BMW to severely reduce drone.

Someone in an earlier post mentioned they were planning on plugging this hole as well. I advise against this because essentially what you will just end up with is straight pipes. No sound can escape into the Helmholtz chamber hence it will drone and defeating the purpose I set out for.

At this point if he's gonna plug up that hole as well you may as well cut the muffler off and just straight pipe it.
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      03-25-2014, 05:47 PM   #109
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Quote:
Originally Posted by dd1981
Quote:
Originally Posted by twelve535i
Quote:
Originally Posted by dd1981 View Post
Because the Helmholtz chamber is still in tact.
It's louder but not to the point where it will emit unbearable drone.
What confused me at first was the fact that the tubing in chamber 2 has no holes, so I didn't see how that could drown out any noise.
Now that I look at the picture again, it appears that there is an additional pipe the runs from chamber 1 into 2 that you have no touched. Is that correct?
Yes that is 100% correct. There is a smaller tube leading into the Helmholtz chamber that still slows some of the sound to drown out. This is naturally designed by BMW to severely reduce drone.

Someone in an earlier post mentioned they were planning on plugging this hole as well. I advise against this because essentially what you will just end up with is straight pipes. No sound can escape into the Helmholtz chamber hence it will drone and defeating the purpose I set out for.

At this point if he's gonna plug up that hole as well you may as well cut the muffler off and just straight pipe it.
Thats why i only spot welded half the holes. Ill do a better video soon
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      03-25-2014, 06:44 PM   #110
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Quote:
Originally Posted by dd1981 View Post
Yes that is 100% correct. There is a smaller tube leading into the Helmholtz chamber that still slows some of the sound to drown out. This is naturally designed by BMW to severely reduce drone.

Someone in an earlier post mentioned they were planning on plugging this hole as well. I advise against this because essentially what you will just end up with is straight pipes. No sound can escape into the Helmholtz chamber hence it will drone and defeating the purpose I set out for.

At this point if he's gonna plug up that hole as well you may as well cut the muffler off and just straight pipe it.
Thanks man.

I might try it out on my own car, but I have two mufflers on my f10, and zero experience. ha ha
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