OEM Muffler mod w/ DPs to retain stock noise level w/ exhaust valve closed

[first350]

I’m new to the F80 M3, but have had previous M3s and other BMWs…here’s some background on what I’m trying to accomplish:

1) I want a quiet exhaust when the valves are closed…but louder when it’s open.
A) Closed: Quiet like OEM w/ exhaust valves closed.
B) Open: I like the DP w/ OEM exhaust sounds/level.
2) I’m getting a tune to delete the Cold Start (our bedroom is below the garage, and I leave for work around 5:30am…the initial start-up wakes up my wife, even when I quickly put it into gear and drive away).
3) Since I’m getting a tune, I figure I’d also get DPs so that I can better utilize the new tune…hard to resist, plus I know I’ll want the extra power later on; I also wouldn’t mind a louder exhaust when the valves are open.

Proposal: My thought is to do the opposite of what the E90/92 M3’s did w/ the OEM muffler…cut open the F80 muffler, and replace some of the piped sections w/ perforated holes to quiet it down further

Does anyone have pictures of what the internals look like…I have the flow diagram (attached), but I’ve yet to see a picture of a real muffler?


*I know some people think modifying the OEM muffler is “poor form”, or unbecoming of a “M3”…I don’t really care. I just want something that sounds good and does what I need; if there’s another aftermarket exhaust that does what I need, I’d be interested…but so far all I could find are mufflers that are louder than OEM.


E90/92 OEM muffler mod (pic 1): Cut open the muffler, and replace the perforated sections (those covered w/ steel wool, see attached pic) with straight section. The steel wool is wrapped around the perforated sections, then there’s insulation in the empty volume that help absorb the exhaust noise.

F80 Muffler: Pic 2

F80 OEM muffler internal flow paths: Pic 3

Proposed mod to muffler (pic 4): Add 4 sections of perforated tubing in the central sections. I didn’t want to add anything in the outer sections, as it appears there’s some unique noise tuning that may be going on (Helmholtz chamber?).


constructive feedback? any personal experiences doing something similar?

[DJM4]

How about gutting the secondary cats?

[gatorfast]

I don't think you will need all that. Just get the tune with cold start removed and you will be amazed at how much quieter it is. Also, I would suggest having the tuner force your exhaust valve closed during startup to mitigate the "startup roar" that most tunes come with.

[first350]

Originally Posted by gatorfast

I don't think you will need all that. Just get the tune with cold start removed and you will be amazed at how much quieter it is. Also, I would suggest having the tuner force your exhaust valve closed during startup to mitigate the "startup roar" that most tunes come with.

I hope you're right...I'm getting the BPM tune, and already selected the "start up roar" off.

[Tommy L Garage]

Reading this post I thought I was reading my own message.
I also wanted a car that’s quiet in the morning when I leave at 5:30 AM and my wife sleeps in the bedroom above the garage.
I also wanted a valve controlled exhaust that’s quiet with flaps closed and loud with them open.

Here’s what I did:
- cold start delete (and roar elimination) - this allows me now to start the car in the AM and even let it idle for a minute or two

With that setup I was able to even try aftermarket exhausts. I had the AA full Signsture exhaust, which was junk. I had just the midpipe and I also had a Dinan muffler. With each setup the cold start was super quiet but you had some loudness with valves open. That loudness was too much for me after a while and didn’t make me like my exhaust sound more.

Now I run just the AA midpipe connected to my ZCP OEM rear Muffler. I’m very happy with it. I also accepted the fact that my car will never sound the way I want it to sound - it’s not sexy v8. The exhaust sound is actually the thing I hate about my car the most.

[first350]

Originally Posted by Tommy L Garage

Reading this post I thought I was reading my own message.
I also wanted a car that’s quiet in the morning when I leave at 5:30 AM and my wife sleeps in the bedroom above the garage.
I also wanted a valve controlled exhaust that’s quiet with flaps closed and loud with them open.

Here’s what I did:
- cold start delete (and roar elimination) - this allows me now to start the car in the AM and even let it idle for a minute or two

With that setup I was able to even try aftermarket exhausts. I had the AA full Signsture exhaust, which was junk. I had just the midpipe and I also had a Dinan muffler. With each setup the cold start was super quiet but you had some loudness with valves open. That loudness was too much for me after a while and didn’t make me like my exhaust sound more.

Now I run just the AA midpipe connected to my ZCP OEM rear Muffler. I’m very happy with it. I also accepted the fact that my car will never sound the way I want it to sound - it’s not sexy v8. The exhaust sound is actually the thing I hate about my car the most.

Thanks for the reply, good to know there's others like me! sounds like I'll hold off until I get the tune & DPs installed...then see if it's quiet enough.

[materialdistractions]

Originally Posted by Tommy L Garage

Now I run just the AA midpipe connected to my ZCP OEM rear Muffler. I’m very happy with it. I also accepted the fact that my car will never sound the way I want it to sound - it’s not sexy v8. The exhaust sound is actually the thing I hate about my car the most.

I share this exact same sentiment. I find a good sounding car completes the driving experience. So, I wanted to improve the way the car sounded a bit. I also went the route of the AA midpipe connected to the a ZCP OEM rear muffler. Although the car does sound better than it did stock in my opinion, it just isn't as good as other cars such as the C63s that I heard the day before I upgraded my exhaust. So I too just accepted the way M3/M4 sounds.

[first350]

Follow up:
I finally installed DPs & the BPM Tune (w/ cold start delete)...
1) w/ exhaust flaps cold: It's quiet...I'd prefer it to be slightly quieter, but it's knocked down enough that chasing 1-3 dB isn't worth it.
2) w/ exhaust flaps open: love it...

BPM tune: wow...super easy, straight forward, and the power is nuts. it's low 40's & rainy here...even on the freeway the tires won't hold. boost builds much faster & the turbo spool noise is more evident.

overall I'm loving it, thanks for all the help!

[CRRobert]

Originally Posted by Tommy L Garage

Reading this post I thought I was reading my own message.
I also wanted a car that’s quiet in the morning when I leave at 5:30 AM and my wife sleeps in the bedroom above the garage.
I also wanted a valve controlled exhaust that’s quiet with flaps closed and loud with them open.

Here’s what I did:
- cold start delete (and roar elimination) - this allows me now to start the car in the AM and even let it idle for a minute or two

With that setup I was able to even try aftermarket exhausts. I had the AA full Signsture exhaust, which was junk. I had just the midpipe and I also had a Dinan muffler. With each setup the cold start was super quiet but you had some loudness with valves open. That loudness was too much for me after a while and didn’t make me like my exhaust sound more.

Now I run just the AA midpipe connected to my ZCP OEM rear Muffler. I’m very happy with it. I also accepted the fact that my car will never sound the way I want it to sound - it’s not sexy v8. The exhaust sound is actually the thing I hate about my car the most.

Have you tried the AA midpipe with the Remus Axle back? Curious to your thoughts. Thanks for all the videos and various options you are trying. Very helpful.