[Mywifes335]

Originally Posted by Alexx911

Is there a reason why you only modified chamber 3? Most people also weld chamber 1.

Anyone returned the fibergas in the second chamber? Or does it not have any effect?
Delete the fibergas or let it in, is there a big difference in sound or drone?

Chamber 1 was a pain to weld all the perforations, but you can definitely do that. The y pipe inside is a complex shape, so replacing it with a straight tube is difficult...but it is doable. Note: if you weld it, the inside of the Y will not be smooth....

There is fiberglass in the 2nd chamber but it has a straight core.

The fiberglass removal will let you hear more sound, as with replacing the perf cores with solid tubing. The reason I have no drone is likely because I have still have the backbox and some of the stock structure.

But outside, it sounds quite loud. Very aggressive. The cabin is very well insulated.

If you rub pure straight pipes, I'm very certain it will drone. I chat with a couple guys running straight pipes, including the Castro setup. Both drone.

The fact that Fabspeeds doesn't drone, I don't know. If you listen to their video you can hear the mic vibrate and resonate at certain RPMs...to me, if there's drone, you'll feel it inside the cabin.

[AK.Alexx]

Ok I get it. So just weld everything in chamber 1 and 3. And delete the fibergass in 1 and 3! Thanks!

I'm also running ER catless. So I think i place my midsilencer back... 1 series is very sensitive for drone when delete midsilencer
But i love the snap and crackles! I hope the muffler mod in combination with downpipe will make it loud and backfire a lot when midsilencer is replaced.

[Mywifes335]

Originally Posted by Alexx911

Ok I get it. So just weld everything in chamber 1 and 3. And delete the fibergass in 1 and 3! Thanks!

I'm also running ER catless. So I think i place my midsilencer back... 1 series is very sensitive for drone when delete midsilencer
But i love the snap and crackles! I hope the muffler mod in combination with downpipe will make it loud and backfire a lot when midsilencer is replaced.

The backfires sound like shotgun shots. Be ready.

Good luck man!

[AK.Alexx]

Thanks mate! Midsilencer delete really brings the snaps and crackles. But in a 1series the drone is way too much. But i'm pretty sure there will be a nice sound even with midsilencer!

[Mywifes335]

Post em when you get the vids!

[lperezp]

Any videos?

[AK.Alexx]

ER Catless downpipe - resonator delete - stock muffler with bypass

I like the sound! But OEM backbox mod will follow.

[AllEyesOnMe]

I just got my muffler delete and wanted to share my thoughts on this.

I have the VRSF downpipe + muffler delete but kept the resonator in tact.

It is very loud on cold-start. If you park in the garage, it's almost 2x as loud as stock exhaust with downpipe.

Inside the cabin, it is very loud. You can hear the bass of the exhaust. There's also drones upon acceleration at around 1.5K that goes away at 2K, then another drone at about 3K-3.6K. If you are going up a steep hill, be ready for some loud drones.

Sound
From the outside, it sounds good. From the inside, it sounds "decent." I say decent because the sound is not "consistent," if that makes any sense... At certain rpms, the cabin would sound good, but at other rpms, the tone of the exhaust makes it sound like a diesel truck. This is subjective though.

Formula for getting gunshots every time:

Get muffler delete + downpipe + 6mt. When you're coming to a stop, downshift from 3rd to 2nd and make sure you're rpm is at about 2.5K-3K, then very, very gently step on the throttle for a split second.

Now onto power.... I feel there's a loss in low-end torque, though some people have said that muffler deletes do not cause any power loss. The outlet of the Y pipe that replaced the stock muffler is 2.25", making it 5" total for exhaust gases to exit. Inlet I believe is the same size as the midpipe.

When I launch, prior to muffler delete, I am pushed back to the seats after the turbo spools up around 2K-2.5K rpm. Now I don't feel that jolt anymore, but a rather linear increase in torque.

Cliff notes:
- If you don't mind the cabin loud at certain rpms and drones, this is for you
- If you want an aggressive sounding exhaust, this is for you
- If you want gunshot overruns, this is for you.
- If you don't care about the feeling of being pushed back in low rpms, this is for you.
- If your gf/wife isn't into cars, a muffler delete+dp is going to annoy them.

** To those with same setup, have you noticed low end torque loss?

[Jadar]

Originally Posted by bubsterino

here's the first video. 228i m sport, muffler delete, everything else stock. magnaflow tips. warm start.

mind you the butterfly valve is removed too so the open/close within the first minute of start up is gone.

I tried filming from a bunch of different angles and distances.

my two cents:

it's entirely too loud for me. I am droning horribly at low rpms, goes away in midrange, and WOT is to me, embarrassing. worst of all, I feel like the car lost its pep.

I am totally self conscious driving around, feathering the throttle so as to avoid unnecessary attention. I could not drive with a passenger. honestly, I'm a little embarrassed driving right now...

I'm shocked honestly - like you, I had no interest in this or any mod whatsoever, but watched so many videos and read so many threads...people basically said you've got nothing to lose and won't break the bank.

I found a reputable shop recommended on the forum. guy couldn't have been nicer, was within the price ranges quoted all over this forum, but man...I'm getting it put back on tomorrow...I can't imagine what this thing sounds like with the resonator removed...

like anything else, YMMV. he simply put a Y pipe on and new tips. I kept my stock muffler / tips so only need to weld that end...

I so wanted to like this, but all I can think of is that it sounds like the pimped out civic this db in high school used to drive. it sounds like crap...

You should have bought a 335/435 or M235 muffler there's plenty of them in the classifieds, put on a dual exhaust diffuser.

Looks oem looks classy sound level goes up a tad and you'd be happy. Plenty here have done it on the 28i cars.

[Blue2]

Originally Posted by AllEyesOnMe

I just got my muffler delete and wanted to share my thoughts on this.

I have the VRSF downpipe + muffler delete but kept the resonator in tact.

It is very loud on cold-start. If you park in the garage, it's almost 2x as loud as stock exhaust with downpipe.

Inside the cabin, it is very loud. You can hear the bass of the exhaust. There's also drones upon acceleration at around 1.5K that goes away at 2K, then another drone at about 3K-3.6K. If you are going up a steep hill, be ready for some loud drones.

Sound
From the outside, it sounds good. From the inside, it sounds "decent." I say decent because the sound is not "consistent," if that makes any sense... At certain rpms, the cabin would sound good, but at other rpms, the tone of the exhaust makes it sound like a diesel truck. This is subjective though.

Formula for getting gunshots every time:

Get muffler delete + downpipe + 6mt. When you're coming to a stop, downshift from 3rd to 2nd and make sure you're rpm is at about 2.5K-3K, then very, very gently step on the throttle for a split second.

Now onto power.... I feel there's a loss in low-end torque, though some people have said that muffler deletes do not cause any power loss. The outlet of the Y pipe that replaced the stock muffler is 2.25", making it 5" total for exhaust gases to exit. Inlet I believe is the same size as the midpipe.

When I launch, prior to muffler delete, I am pushed back to the seats after the turbo spools up around 2K-2.5K rpm. Now I don't feel that jolt anymore, but a rather linear increase in torque.

Cliff notes:
- If you don't mind the cabin loud at certain rpms and drones, this is for you
- If you want an aggressive sounding exhaust, this is for you
- If you want gunshot overruns, this is for you.
- If you don't care about the feeling of being pushed back in low rpms, this is for you.
- If your gf/wife isn't into cars, a muffler delete+dp is going to annoy them.

** To those with same setup, have you noticed low end torque loss?

Good write up. I want to do a muffler delete on my M240 when I get it but my big concern is loss of low end torque. Very interested to hear others experiences with this too.

[Mr_White]

Originally Posted by starvmarv

So I got around doing some calculations for creating a Helmholtz resonator (which is basically a branched off Closed-Pipe resonator or J-Pipe, as it is most commonly known) to reduce or even eliminate specific frequency drone that occurs at a certain RPM (Honda S2000 uses this method in its factory exhaust system to eliminate drone)
**Please note that the method below, will only reduce that certain frequency, so if you want to eliminate the low end drone you’ll still have the drone at the 2500 and above range and vise versa). Basically the sound wave will enter the closed pipe, reach the end, bounce back and cancel out.

The Formula:

[(1125 f\s divided by Hz ) divided by 4] multiplied by 12 = pipe length in inches

1125 f\s – speed of sound in feet per second
Hz – the measured frequency of the drone you want to reduce or eliminate at a certain RPM
4 – the 1\4 wave length
12 – converting it into inches
Pipe length – the length of the pipe that branches out of the stock system

Tools:
You will want to download a frequency counter app on your SmartPhone or tablet. (Having a computer with a good quality mic will give you the best results, but I had none)
You will want a camera or a second person to view the RPM and Frequency (Hz) to determine what frequency you find most annoying at a certain RPM to reduce (this way the driver keeps eyes on the road at all times)

After you have gathered that information plug in the numbers into the formula

At 3300 RPM I was at around 150Hz
At 2500 RPM I was at around 143Hz
At 1500 RPM I was at around 125Hz
*This was using the app. Not sure if it is 100% accurate but it is good enough to give you a rough estimate

For example, if I want to reduce the drone at cruising level I will want to see what RPM I am stable at 50MPH. Say for example 1500RPM.

[(1125f\s ÷ 125hz)÷ 4] x 12 = 27inches

To reduce the drone at 1500RPM you will need to make a 27 inch pipe (closed off at one end) branching out of the exhaust.

The shape of the pipe should’t matter, but most people make a J shape due to space restriction. Some have said closer to the engine will be most effective, others say it does not matter. I had no choice but to do it at the end right before the split to the pipes due to space.

You will want to use the same size pipe for the resonator as your exhaust. (but you should be fine going under half an inch).

Because the pipe is closed off, no air will go in it, therefor performance will not be at all effected. Only the sound waves enter.

MY RESULTS (STILL A WORKING PROGRESS):

I went to my welder guy, and he was able to create the pipe per my specification and I can honestly say I am very happy with the results. There is still the tiniest bit of drone but the reduction is noticeable in the cabin. I feel like I can make it better, but need more trial and error. What I should have done (and what I will do sometime in the next few weeks, is make the J pipe an open, then add a “closed ended” sleeve at the end of it so that I can adjust the length to fine tune it.

I’ll keep you guys posted






(I was going to do a before and after video, but the camera mic isn't the best, so hard to tell the difference. Here is a very short video after J pipe install, driving up a small incline, where drone is most noticeable in these types of set up. As you can tell it isn't at all bad anymore)

Acceleration video:

PLEASE NOTE. I tried my best to get the most accurate information possible above. If you see something that is not accurate, please correct me . I am not responsible for any time, damages, or money wasted trying this mod. It is still a working progress and frequency measurements may be off depending on App\Software and Hardware used (such as microphone quality or an off calibrated measurement system\tool). Please use this guide as a reference only. Thanks.
*I like being the guinea pig sometimes

So what length J Pipe did you end up going for?

[rahuladdala@yahoo.com]

thanks everyone for sharing the views. I just started my research to get sporty sounds out of my M235i but i am not open with voiding my cars factory warranty. Can someone suggest if muffler delete or after market exhaust will void BMW Factory warranty ?

[jondagger]

Originally Posted by rahuladdala@yahoo.com

thanks everyone for sharing the views. I just started my research to get sporty sounds out of my M235i but i am not open with voiding my cars factory warranty. Can someone suggest if muffler delete or after market exhaust will void BMW Factory warranty ?

neither will... so go right ahead.. My suggesting is to get a muffler swap like the link below, not tooo pricey and good product... straight pipe is obnoxious IMO.. People sell the M Performance muffler used all the time...

https://x-ph.com/active-autowerke-bm...-back-exhaust/

Now if you are daring, just get a chargepipe, downpipe, and resonator delete with a JB4. You get a huge exhaust note when you punch it plus loud pops when you please, yet quiet when you need it. Also +70hp or so.... In the rarest of cases where you will actually use the BMW warranty for engine related issues, just take the mods off. no traceability really