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      03-23-2013, 10:30 AM   #1
dd1981
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Post Stock F30 335i Axle Back Exhaust Muffler Modification and Dissection

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As always, my curiosity gets the best of me. I planned on doing this for some time now, pretty much since I installed my M perfromance axle back.

It goes back to when I saw a few people modifying the e90/92 M3 exhaust by replacing the perforated tubes, and the result was an amazing sound for very few $$$.

The plan was to replace them on the f30 muffler and reinstall it on my 335i and see what the result would be. But due to chamber 1 and the shape of the pipe this seems pretty much out of the question, as there would be way to much custom work and too much labor involved. Im trying to keep this as simple as possible.

So plan B is to open up the muffler all the way, so that I have access to both top and bottom, and spot weld every single hole individually in chamber 1 and 3.

Ill update as I go.


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      03-23-2013, 10:51 AM   #2
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I have been waiting for this! But this makes me relize the F30 stock muffler is a well designed unit so well I can't believe it. It's so quiet with this design I am a little shocked. But it does have a giant Hemholtz Chamber.
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      03-23-2013, 11:17 AM   #3
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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?
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      03-23-2013, 11:44 AM   #4
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Quote:
Originally Posted by shivaswrath View Post
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
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      03-23-2013, 11:50 AM   #5
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Quote:
Originally Posted by dd1981 View Post
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
The second chamber you want to keep that is the hemholtz chamber it's what kills drone. Taking out the the 1st and 3rd chamber like you said by welding the holes should work. Nice clean lines that is good angle grinder work.
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      03-23-2013, 12:22 PM   #6
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The second chamber you want to keep that is the hemholtz chamber it's what kills drone. Taking out the the 1st and 3rd chamber like you said by welding the holes should work. Nice clean lines that is good angle grinder work.
Yes, the 2nd chamber Im not touching. Thanks, it helps when you outline and just cut by following the lines.

If I try to replace the tube in chamber 1 I forsee issues and it wont be cost effective. Its not like in the m3 muffler where they are just 2 straight perforated tubes, you cut replace and weld.

It would pretty much looks like this. Also sorry Im not the greatest with photo shop but its a rough draft of what its suppose to look like.
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      03-23-2013, 03:21 PM   #7
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Wow.. Please do keep us updated on the result!! Im looking to do this same thing with mine!

My main concern is drone, but since chamber 2 is untouched i think the result will be quite satisfactory!

Are the materials you removed only for sound supression?
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      03-23-2013, 04:03 PM   #8
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Yes, the 2nd chamber Im not touching. Thanks, it helps when you outline and just cut by following the lines.

If I try to replace the tube in chamber 1 I forsee issues and it wont be cost effective. Its not like in the m3 muffler where they are just 2 straight perforated tubes, you cut replace and weld.

It would pretty much looks like this. Also sorry Im not the greatest with photo shop but its a rough draft of what its suppose to look like.
I think you got the right idea I have done this before. I did it trial and error and actually before I welded the muffler up I used exhaust tape so I could hear how each change sounded. I want to do this with my stock exhaust so I can sell my M Performance.
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      03-23-2013, 07:20 PM   #9
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Quote:
Originally Posted by Koer View Post
Wow.. Please do keep us updated on the result!! Im looking to do this same thing with mine!

My main concern is drone, but since chamber 2 is untouched i think the result will be quite satisfactory!

Are the materials you removed only for sound supression?
Yes it was just for sound deadening. It felt like a wig lol. Not sure what the material was. I think as for drone there will be some because even my m perf muffler gets a tad bit but only when driving in comfort or Eco when low rpm and all gears are in play. Ill post up as I go, I figure about another a week or so ill have it wrapped up.
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Originally Posted by buildbright View Post
I think you got the right idea I have done this before. I did it trial and error and actually before I welded the muffler up I used exhaust tape so I could hear how each change sounded. I want to do this with my stock exhaust so I can sell my M Performance.
You and are thinking alike . I want to see if this works and ill sell my m perf muffler as well. That's a nice move with the muffler tape and testing it. Reading your post and your past experience in doing this really makes me think I'm doing the right thing and it will be a success. Ill defoentely post up pics and sound clips.
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      03-23-2013, 09:05 PM   #10
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Does any one make a muffler delete?
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      03-23-2013, 09:16 PM   #11
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Quote:
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Does any one make a muffler delete?
Not a specific manufacturer that I know of, but I have seen a couple of people custom fabricate their own exhaust with a muffler delete. Sounded pretty good actually. There are some threads I'm here about it you'll have to search it.
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      03-23-2013, 09:17 PM   #12
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I fabricated my own muffler delete, I am surprised a company has not started to make one yet.
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      03-23-2013, 10:24 PM   #13
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Quote:
Originally Posted by dd1981 View Post

You and are thinking alike . I want to see if this works and ill sell my m perf muffler as well. That's a nice move with the muffler tape and testing it. Reading your post and your past experience in doing this really makes me think I'm doing the right thing and it will be a success. Ill defoentely post up pics and sound clips.
Yes I agree I was trying to buy an extra stock exhaust because I was worried the stock muffler would be a mess but now I am going to my exhaust guy next week. Thanks for being fearless and inspiring me. Now you got me to wonder what the M Performance muffler looks like. I guess great minds think alike lol
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      03-24-2013, 11:10 AM   #14
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Yes I agree I was trying to buy an extra stock exhaust because I was worried the stock muffler would be a mess but now I am going to my exhaust guy next week. Thanks for being fearless and inspiring me. Now you got me to wonder what the M Performance muffler looks like. I guess great minds think alike lol
Indeed great minds think alike . I'm curious about the m muffler as well but I'm not sure if want to cut into it, it may turn away a potential buyer if I go to sell it.
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      03-27-2013, 02:11 PM   #15
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Sorry to bring this off topic, but what is that black module attached to the drivers side exhaust pipe?

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      03-27-2013, 02:59 PM   #16
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Sorry to bring this off topic, but what is that black module attached to the drivers side exhaust pipe?

That is the actuator that opens and closes the butterfly valve.
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      04-13-2013, 04:14 PM   #17
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Really interesting, were you able to complete and test?
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      04-13-2013, 06:32 PM   #18
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Really interesting, were you able to complete and test?
It's out in a shop getting welded. My friends dad is doing it he said the inside pipe will be very easy to weld since its steel. The canister is aluminum and is a PITA to weld aluminum so he quoted $200 for the gas used and his labor.
If its successful (I believe it will be) it will be a well worth $200 mod, as opposed to spending a grand on the m performance axle back.
If unsuccessful in what I'm trying to achieve, we'll I threw away $200 on an experiment and you guys got to see the interior of the muffler

Stay tuned
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      04-13-2013, 09:06 PM   #19
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Very interested!
Can't wait to see the results.
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      04-14-2013, 08:52 PM   #20
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Quote:
Originally Posted by dd1981 View Post
It's out in a shop getting welded. My friends dad is doing it he said the inside pipe will be very easy to weld since its steel. The canister is aluminum and is a PITA to weld aluminum so he quoted $200 for the gas used and his labor.
If its successful (I believe it will be) it will be a well worth $200 mod, as opposed to spending a grand on the m performance axle back.
If unsuccessful in what I'm trying to achieve, we'll I threw away $200 on an experiment and you guys got to see the interior of the muffler

Stay tuned
Just removing the damping material will change the sound, making it louder and perhaps even a bit deeper.

If you consider that low frequencies are also longer waves, then allowing that wave to travel through to the outlet without being broken up will result in a deeper sound. Long waves can also bend around corners like through the tubing. That's why in a house we can still hear the bass coming from the stereo even if we're in another room down the hall.
Your idea to close off those holes is a "sound" idea, as those holes are where the longer sound wave is being broken up.
That additional damping material further absorbs the broken wave energy to keep things quieter.

I think you're going to get a much louder and deeper tone, but will it sound pleasant? THAT is THE question.
If it does sound good I'll be surprised considering that manufacturers spend time tuning mufflers and exhausts systems not just for flow but sound quality. It'll be a very happy surprise if the louder sound is also a pleasant one. You may find that only closing half or one side of the holes will yield a better tone.
Maybe you should have done only one side at a time.
That way you would know if you're on the right track.
But, too late now. If the sound is ugly you could then try drilling some holes back in.

I had a Yamaha V-twin a few years back with a very anemic and very quiet exhaust due to the same type of design as our stock mufflers. People experimented and came up with some ideas. I used the recommendations and did the drilling. Yes, the sound was louder and deeper, but the quality of the sound sucked.
So, I opted for a set of low cost slip on mufflers made by Jardine. The result was louder, deeper, but a much better and mellower sound quality.
The best experimental experience I had was with my former Honda VFR750.
It's a V-4 engine. I had a nice though quiet Yoshimura slip on muffler.
One day I took off the slip on and fired up the V-4. WOW, man that engine had a cool sound and with just the headers the sound was glorious. But now way I could ride it around, it was just too freaking loud.
I've loved the sound of V4 engines ever since. Too bad they're not common. I'd love an auto maker to make a V4 for a car. That configuration yields great torque, and what a sound, think 2 V-Twins beating against each other.
I digress, sorry.

I want to hear your frankenmuff experiment. Let me know when it's done and I can come out and take a listen.
PM or email me.

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      04-14-2013, 09:18 PM   #21
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Quote:
Originally Posted by RPM90 View Post
Just removing the damping material will change the sound, making it louder and perhaps even a bit deeper.

If you consider that low frequencies are also longer waves, then allowing that wave to travel through to the outlet without being broken up will result in a deeper sound. Long waves can also bend around corners like through the tubing. That's why in a house we can still hear the bass coming from the stereo even if we're in another room down the hall.
Your idea to close off those holes is a "sound" idea, as those holes are where the longer sound wave is being broken up.
That additional damping material further absorbs the broken wave energy to keep things quieter.

I think you're going to get a much louder and deeper tone, but will it sound pleasant? THAT is THE question.
If it does sound good I'll be surprised considering that manufacturers spend time tuning mufflers and exhausts systems not just for flow but sound quality. It'll be a very happy surprise if the louder sound is also a pleasant one. You may find that only closing half or one side of the holes will yield a better tone.
Maybe you should have done only one side at a time.
That way you would know if you're on the right track.
But, too late now. If the sound is ugly you could then try drilling some holes back in.

I had a Yamaha V-twin a few years back with a very anemic and very quiet exhaust due to the same type of design as our stock mufflers. People experimented and came up with some ideas. I used the recommendations and did the drilling. Yes, the sound was louder and deeper, but the quality of the sound sucked.
So, I opted for a set of low cost slip on mufflers made by Jardine. The result was louder, deeper, but a much better and mellower sound quality.
The best experimental experience I had was with my former Honda VFR750.
It's a V-4 engine. I had a nice though quiet Yoshimura slip on muffler.
One day I took off the slip on and fired up the V-4. WOW, man that engine had a cool sound and with just the headers the sound was glorious. But now way I could ride it around, it was just too freaking loud.
I've loved the sound of V4 engines ever since. Too bad they're not common. I'd love an auto maker to make a V4 for a car. That configuration yields great torque, and what a sound, think 2 V-Twins beating against each other.
I digress, sorry.

I want to hear your frankenmuff experiment. Let me know when it's done and I can come out and take a listen.
PM or email me.
Yeah it may indeed sound like crap. We shall find out soon. Im leaving the packing material in there, i think it will help with droning. Not sure if just want to do one side welding, and if there is little or no change because the sound is still escaping Ill be pissed lol. To reopen and reweld the muffler again will just be to costly to make the project worth wile and to proceed would just be throwing another $100-$200 to reweld the canister.

Im gonna pray that is sounds good, as I got my idea form an E92 M3 project I saw on youtube. The cut and replaced the perforated pipes instead of just welding the holes up, but those pipes were perfectly straight and easy to cut and weld. The F30 interor piping is curved and oval so to speak. Finding another pipe like that is a long shot and a waste of time and cash.

As soon as Im done Ill throw up a video. And youre more then welcome to check it out in person if it sounds good. Even if it sounds like crap Ill still post up the vids just to show you guys.
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      04-14-2013, 11:07 PM   #22
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It should like a muffler delete which sounds pretty good on our cars.
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