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Thread: rear muffler internals

  1. #1
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    rear muffler internals

    I was curious to see what the internal construction of an OEM muffler looks like.
    So I decided to cut one open and take a few pictures.
    I thought they might be of interest for some people.

    Next step for me will be to take out all the piping and modify them internally.












  2. #2
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    Don't you think it's too much back pressure with these mufflers?

  3. #3
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    Quote Originally Posted by bmw528e11 View Post
    Don't you think it's too much back pressure with these mufflers?
    back pressure isn't generated in the rear mufflers. The cat converters are key to back pressure on this exhaust system.



  4. #4
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    The stock muffler is also a Dinan muffler after dinan cuts have the material out.

  5. #5
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  6. #6
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    and if you put straight pipes infront of them your car sounds like a tractor
    I've tried, that was my exhaust version 1. no cats, straight pipes into OEM mufflers = tractor
    -Egil (my name)

    2012 ///M550xd touring
    1990 850Ia Hartge Supercharged.
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  7. #7
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    Good God no wonder the weight so damn much.... And yes anything added after the Headers is a restriction. Blow thru a long straw then blow thru a short one if you think im wrong.

  8. #8
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    Looks like it could have been a prop in max max fury road

  9. #9
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    Quote Originally Posted by Noggie View Post
    and if you put straight pipes in front of them your car sounds like a tractor
    I've tried, that was my exhaust version 1. no cats, straight pipes into OEM mufflers = tractor
    You should hear mine Nog with muffler Delete
    Last edited by smokum; 04-26-2016 at 08:18 PM.

  10. #10
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    Quote Originally Posted by smokum View Post
    You should hear mine Nog with muffler Delete
    I know how that sounds, Adrian's car used to have that mod.
    If I had only known that 5 years ago

    Instead I did the horrible long route of trial an error...... mostly error.
    Version 1:
    As explained, Got some Engl Straight pipes to replace the cat's and his X-pipe, into stock mufflers.
    Sounded like a tractor.

    Version 2:
    Added Wokke's rear mufflers. So loud you needed hearing protection in the car, crazy drone, impossible to have a conversation or listen to music/radio inside the car.
    Video clip: https://www.youtube.com/watch?v=myzQhFLj5G8

    Version 3: Added Engl 200-cell race cat's. better, but still loud, drones like crazy
    video clip: https://www.youtube.com/watch?v=ziX1Jb70JZw

    Version 4: Replaced Engl x-pipe with Wokke X-pipe. A lot less drone, still a bit on the loud side, but it's ok.
    I can listen to music, talk with passengers, and during normal cruise its about as quiet as stock, rolling in towards intersections etc where the rpm is below 1500 its drones a little, and when you use the throttle its really loud.

    Video: https://www.youtube.com/watch?v=AJNfOIjn3FE

    Might do a version 5 just to get it a little more quiet
    Last edited by Noggie; 04-27-2016 at 08:47 AM.
    -Egil (my name)

    2012 ///M550xd touring
    1990 850Ia Hartge Supercharged.
    2004 M3 (sold)


  11. #11
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    Blimey, that was quite a journey!
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  12. #12
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    Quote Originally Posted by Timm View Post
    Blimey, that was quite a journey!
    Yeah, so I have come to know what different things do to the exhaust on these cars.

    One thing I noticed is that the engine response is greatly improved with a free flow exhaust.
    By that I mean. If you rev the engine, the process is much much quicker with free flowing cat's and no center resonator.

    In retrospect, doing such a major redesign of the cars exhaust system, I would have picked some larger cat's, the 200-cell are just too small, perhaps something in the 400-cell range would be much better. or as Wokke does, use some sturdy mufflers to replace the cat's.

    The simple, cheap way to get a sweet sounding V12 is to just remove the rear mufflers and replace them with straight pipes with exhaust tips on.
    The more expensive route is to do a "cat-back" system, i.e replace the center resonator with an X-pipe, and some rear mufflers.
    You should NOT mess with the cat's unless they need to be replaced.
    -Egil (my name)

    2012 ///M550xd touring
    1990 850Ia Hartge Supercharged.
    2004 M3 (sold)


  13. #13
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    What's inside the Center Resonator?

  14. #14
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    Quote Originally Posted by Dr. T View Post
    What's inside the Center Resonator?
    03.JPG
    Last edited by wokke; 04-28-2016 at 10:50 AM.



  15. #15
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    Dinan cut out that front hoop and re-welded the cases back together to create their "performance mod" that they charged a fortune for... and they replaced the tips too, but that's for vanity, not function.

  16. #16
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    Quote Originally Posted by cartoonz View Post
    Dinan cut out that front hoop and re-welded the cases back together to create their "performance mod" that they charged a fortune for... and they replaced the tips too, but that's for vanity, not function.
    I would not Doubt it one bit, I dont know how that guys get away with half the crap he does, Then charges the Customer up the ass for it... DOUCHE LEVEL ULTRA!

    BTW i can say that because We met the guy at a meet in Mountain View
    Last edited by smokum; 04-28-2016 at 12:09 PM.

  17. #17
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    Quote Originally Posted by Noggie View Post
    You should NOT mess with the cat's unless they need to be replaced.
    Other than the inflated emissions, is there a reason why you wouldn't want to mess with the cats to free up the exhaust flow?
    i.e. replacing with a quality piece such as HJS, etc.....

  18. #18
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    I got a huge gain in power when I replaced both cats with 200-cell 'sports' versions... Blooming noisy though!
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  19. #19
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    Quote Originally Posted by whiteghost1 View Post
    Other than the inflated emissions, is there a reason why you wouldn't want to mess with the cats to free up the exhaust flow?
    i.e. replacing with a quality piece such as HJS, etc.....
    As long as your cat's are working, and there is no issues, i.e rattle etc. I would recommend leaving them alone.
    You might end up with sounds you don't want in your car.
    -Egil (my name)

    2012 ///M550xd touring
    1990 850Ia Hartge Supercharged.
    2004 M3 (sold)


  20. #20
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    Quote Originally Posted by Timm View Post
    I got a huge gain in power when I replaced both cats with 200-cell 'sports' versions... Blooming noisy though!
    Do you figure that is because they were tired/partially clogged, or because the factory cats are that restrictive?

  21. #21
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    Quote Originally Posted by whiteghost1 View Post
    Do you figure that is because they were tired/partially clogged, or because the factory cats are that restrictive?
    Keep in mind that the OEM cats we can compare to are normally 20 years old or even older. And the ceramic technology is definitely not superior to the newer steel cats.
    The fact that ALPINA replaced the OEM cats with stainless steel versions speaks foir itself I guess. But as Noggie pointed out correctly, they do change the sound quite a bit.
    Go for 100 or 200 cell units if you want a more aggressive sound, go for 400 cells if you want to stick closer to the original.



  22. #22
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    Quote Originally Posted by cartoonz View Post
    Dinan cut out that front hoop and re-welded the cases back together to create their "performance mod" that they charged a fortune for... and they replaced the tips too, but that's for vanity, not function.
    I can't say whether the Dinan exhaust adds any performance due to the other mods which obviously do... but I can say that the exhaust is super quiet at idle and at higher rpm's.

    -JRW

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    Built for PGA Pro Mark Calcavecchia
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  23. #23
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    Quote Originally Posted by smokum View Post
    I would not Doubt it one bit, I dont know how that guys get away with half the crap he does, Then charges the Customer up the ass for it... DOUCHE LEVEL ULTRA!

    BTW i can say that because We met the guy at a meet in Mountain View
    That's a given. On the set of "Dinan performance" mufflers I originally had on The Beast, a juvenile pigeon could have made better welds.. .it was way bad.
    As for Steve's crap... you want to see evidence of how bad he really is? Look up what happened with his Z8 performance upgrade debacle. Seems, the Dinan School of "Get a Bigger Hammer" was in full swing and they literally destroyed several Z8 cars.. and then were forced to purchase brand new complete Z8 shells from BMW to fix the problems they created.

  24. #24
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    I guess you can't compare Dinan of 2016 to Dinan of the 90's.
    Our cars were typically handled back then, and I have heard a lot of different things happening to cars from that era.
    That they today are a much bigger company, with much more experience and range of products is a completely different story.
    -Egil (my name)

    2012 ///M550xd touring
    1990 850Ia Hartge Supercharged.
    2004 M3 (sold)


  25. #25
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    haha... except the Z8 program disaster was in the 2000's era.
    They may be better recognized, but the underlying philosophy is the same.

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