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Thread: Changed Cats and Deleted Muffler

  1. #1
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    Changed Cats and Deleted Muffler

    Hi,
    Okay so I removed the cats and put glass packs in and deleted the muffler and is now straight through. It sounds great but when it hits 3000 it gets TOO loud lol. It sounds like a rumble rattle fart slap..(reverberating) ahh would anyone know how to oversome this issue? Should I just put the muffler back on?


    Last edited by AusFreak; 08-16-2017 at 01:09 PM.

  2. #2
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    no, over time you will go deaf and then the tone will be just "right"....lol

  3. #3
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    01 750il, E38/9 Parts
    Do you still have a resonator in place?

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  4. #4
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    i think thats the small things before the cats? they are all gone. I think im going to put the muffler back on and see what happens

    This is the exhaust system
    http://www.realoem.com/bmw/enUS/show...diagId=18_0177

  5. #5
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    Those are the catalytic converters


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  6. #6
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    What kind of mpg change did you get if any? I had the CATs replaced and the installer could not fit the resonators back in. I lost almost 2 mpg.

    PS mine sounds the same tone with the OEM muffler, probably is quieter but at 4000 it becomes raspy and can set off some car alarms. Once the car warms up it is less noisy.

  7. #7
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    im overseas and fuel doesnt cost much so i havent checked. I only had the car done a few hours ago and right now im about to go back put the mufflers back on and see what happens

  8. #8
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    Ive had the muffler put back in and it sounds standard again. Im going to have the cats removed and see what happens, will update you.

  9. #9
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    Quote Originally Posted by AusFreak View Post
    It sounds great but when it hits 3000 it gets TOO loud lol. It sounds like a rumble rattle fart slap..(reverberating) ahh would anyone know how to oversome this issue?
    Look into an H-pipe and/or X-pipe.


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  10. #10
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    what do you think of something like this http://www.autoanything.com/exhausts...A2672A0A0.aspx and then straight through i guess.
    I am going to remove the cats and leave the muffler and see what that sounds like. Just experimenting.

  11. #11
    Join Date
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    95 540i,98 328i, 93 325i
    I have just a muffler delete with straight pipes and I thought it was ignorantly loud even with the cats and resonators.
    https://streamable.com/p8gqn

    I thought it would sound great because the straight pipes on my 540 sound glorious. Totally different worlds.
    https://streamable.com/u32c5

    No real reason to get rid of cats and resonators unless you want to get pulled over everywhere and ruin peoples day.
    Last edited by Beer+Oversteer; 08-17-2017 at 11:28 AM.

    1998 318i m52 swap 3.38 lsd, 1995 540i/6 speed (SOLD), 1993 325i, 1999 328is m-sport, 1996 328i GT35

  12. #12
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    sounds pretty savage. Unfortunatly mine didnt sound normal haha.

    Ok an update, The cherry bombs are still on as cats and put the muffler back on and deleted the silencer and Y pipe from inside the muffler and it now sounds reaaaaaallly nice, take a look

  13. #13
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    Quote Originally Posted by AusFreak View Post
    i think thats the small things before the cats? they are all gone. I think im going to put the muffler back on and see what happens

    This is the exhaust system
    http://www.realoem.com/bmw/enUS/show...diagId=18_0177

    The items near number 1 are CATs the smaller items to the right are resonators. Note you have the OBD I design with one oxygen sensor (29) thus the 2 to 1 pipe before the CATs ... still dual separate inlets. Resonators will probably remove the lower frequency thump sounds while the cats naturally reduce all sounds. The muffler reduces the low and some high. Guess that's why they are called tuned exhaust. but most companies cannot touch the CAT and resonators thus CAT back replacement.

  14. #14
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    Good info thanks mate car sounds alright now, going to do the interior this week and week after will have the car painted black and then hopefully start the turbo job

  15. #15
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    Turbo will completely change the sound of the car.


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