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BMW M5 F90 (2018+) General Forums Engine, Exhaust, Drivetrain, Tuning Modifications    Noise with just catless downpipes?

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      04-28-2021, 04:50 PM   #1
samj2k
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Noise with just catless downpipes?

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Hello,

I have a 2018 F90 M5, it’s currently stage 1.

It has the M Sports Exhaust on it and I was thinking of going full downpipes to remove the primary and secondary cats for stage 2.

I use it as my daily, and don’t want to turn up at the office with an obnoxiously loud car. Does anyone have a video of one with just downpipes with a stock or M Sports exhaust on? Or know how much noise it will add?

Thanks
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      04-29-2021, 06:47 AM   #2
pbonsalb
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I am curious as well, but will be waiting until the warranty expires. I have overmodded my last few cars to the extent my wife won't ride in them because they are too loud and rough. This time, I plan to stay more civilized (I am keeping one of those older loud and rough cars for fun).
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      04-29-2021, 02:50 PM   #3
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I went for a full remus exhaust, deleting the OPF’s and resonator, without touching downpipes and cats. I can say it is too loud and it gave me some drone.
If I were to do it again I would probably just delete the resonator or the OPF’s.
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      04-29-2021, 05:25 PM   #4
pbonsalb
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I am more into performance than sound, so my interest is in removing restrictions like the cats. The rest of the system has a much more minimal effect on performance. But I may not do downpipes if it makes the exhaust obnoxiously loud or adds drone.
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      04-29-2021, 05:43 PM   #5
samj2k
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Quote:
Originally Posted by pbonsalb View Post
I am more into performance than sound, so my interest is in removing restrictions like the cats. The rest of the system has a much more minimal effect on performance. But I may not do downpipes if it makes the exhaust obnoxiously loud or adds drone.
Completely agree. My car is pre OPF anyway so is already reasonably loud. I would like the performance gains from the primary and secondary cat removal, but without it being too loud. It’s a shame someone doesn’t make downpipes with silencers. I guess I could get some fabricated?
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      04-29-2021, 06:03 PM   #6
pbonsalb
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May not be necessary - need to get input from those with them as to the sound increase. They are stubby fat cats and I have not seen mufflers or resonators that look like they will fit. I have a year or two to learn since I don’t want to void my warranty. The rest of the exhaust is pretty tame, which is why there is active sound. Maybe turn off the fake sound and the exhaust sound be ok with just the cat deletes. Another option is to leave the secondary cats.
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      04-30-2021, 07:41 AM   #7
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Quote:
Originally Posted by pbonsalb View Post
May not be necessary - need to get input from those with them as to the sound increase. They are stubby fat cats and I have not seen mufflers or resonators that look like they will fit. I have a year or two to learn since I don’t want to void my warranty. The rest of the exhaust is pretty tame, which is why there is active sound. Maybe turn off the fake sound and the exhaust sound be ok with just the cat deletes. Another option is to leave the secondary cats.
I was thinking of leaving the secondary cats, but I’ve already got the evolve stage 2 tune ready to upload, and not sure how well it would work with just primary deletes. Imagine I would have to take the car to them for a custom map. Stage 1 is quick enough for now. Hopefully someone has feedback just running primary and secondary pipes on a stock exhaust.

On another note, how do you actually turn off the active sound? Is it coding or an option.
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      05-26-2021, 01:01 PM   #8
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Quote:
Originally Posted by samj2k View Post
Hello,

I have a 2018 F90 M5, it’s currently stage 1.

It has the M Sports Exhaust on it and I was thinking of going full downpipes to remove the primary and secondary cats for stage 2.

I use it as my daily, and don’t want to turn up at the office with an obnoxiously loud car. Does anyone have a video of one with just downpipes with a stock or M Sports exhaust on? Or know how much noise it will add?

Thanks
I'm running only cat less Supersprint Downpipes on my car with OEM M sport exhaust( comes standard on the comp). I think this is the best blend of daily driving and sound. Except cold starts are extremely loud.
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