stock exhaust mod

[meko]

Nice. Now is that both perforated pipes per side (4 total) or just the bigger ones (2 with more holes)?

[F82_SID]

Originally Posted by meko

Nice. Now is that both perforated pipes per side (4 total) or just the bigger ones (2 with more holes)?

That is just the two larger perforated pipes sealed with another pipe welded over them. I didnt think it was necessarily to seal the smaller pipes since the stock wrapping covers them pretty good already. Here are some picts of what I had done...

[TMR]

Is there anyone running catless with a modded stock muffler?

[EliteM3]

So, now that I have had another day with the car, I am loving it more and more. I only did the 2 perforated pipe method, and the sound is growing on me. I did go behind the car with the cold start in effect, and it is MUCH louder than stock, then calms down once that cold start is over. In the car, on the freeway, when you gun it, it does in-deed sound delicious.

Yes, I do wish it was a tad louder inside, I am sure I am probably pretty loud to everyone else, but hopefully not obnoxious.

Great mod, and I am extremely happy i did it. I had my muffler guy cut out the old pipes and replace with 2.5" T304 stainless. My guy charged me $220 (i provided the stainless), but said with the work involved, next time it would be $320. The video doesn't show that there are 2 layers of stainless muffler to cut through and then weld back on. I took a risk to let him perform his first stock exhaust mod on my car, but it worked out in my favor.

Do it...you will love it

[meko]

Great info I'm sold. Just cant decide if I want to wrap the pipe, replace it entirely or cover it with a cut piece of stainless like you did. Think I like your method which will be easier to just weld on top. Even if weld is not perfect you can't do any damage because original pipe is still in place and was designed with perforated holes in the first place. Any other helpful hints or suggestions? Painting can black?

[EliteM3]

Well, I spoke to my muffler guy, and gave him a few options for what I have seen others do.

1) wrap the pipe with exhaust tape.
- He said he is yet to find one that will last, and would never think to put that on there. once it goes, you have to open the can up again and redo it.

2) cut a larger pipe in half (down the middle) and weld over the smaller pipe.
- He said that is more work that just replacing the pipe entirely, and probably more difficult since there is a substantial bend in one of the perforated sides.

3) cut out entirely and replace with stainless
- Best, most permanent and troublefree option.

So we opted for Option #3.

Next, when you cut it open, you will find that the muffler is double walled. Because of that, you have to either weld each piece back on one at a time (4 full welds), or weld both peices together and weld on once. We opted for welding together. He said he doesn't want any chance of rattles, so tacking the peices together is a no no. He welded all the way around (he said like welding paper together). Then welded onto the muffler.

Finally, we sprayed hi-temp paint over the welds on the outside of the muffler. Unfortunately, I did not specify the color...when I asked if he could spray over the welds, he did, but used green. why? I do not know . You can't see it unless you are under the car looking for it, but still not my first choice. My suggestion would be to spray silver to semi-match the muffler, so it looks more OEM. Others paint matte black, and that would work too, because you probably don't want to see any muffler from behind the car, and matte black would be best for that. The whole point is to try to protect the welds from rust.

If anyone is looking for a muffler guy to do this work in Morgan Hill, John at A-1 Muffler did a great job on mine and is comfortable repeating. It will be $320 plus the pipe (he only has aluminized steel in the shop)...which you can get on Amazon for $10. When he measured the pipe lengths, they both came out to be under 5.5 inches, so a 12" piece of 2.5" T304 16 gauge (.065) stainless steel is all you need.

Let me know if you have any more questions.

[KJ]

Originally Posted by tibra1

Couldnt disagree more..if I wanted a straight thru setup I would just get a set of magnaflows and be done with it..and lose about 30 lbs of exhaust weight in the process..single perforated pipe method is the most refined sound w/o being obtrusive..

+1

[m3an]

I don't know how many times I can post it..... A muffler delete sounds exactly the same, costs less, you can put custom tips on, and you eliminate a ton of weight and the ugly stock look.

[TMR]

Originally Posted by talontid

I don't know how many times I can post it..... A muffler delete sounds exactly the same, costs less, you can put custom tips on, and you eliminate a ton of weight and the ugly stock look.

Ok, how does a muffler delete sound without cats?

[IbanezGod]

guys at autocouture sent me this video. Sounds great, hopefully can have it done ASAP

[KJ]

Originally Posted by talontid

I don't know how many times I can post it..... A muffler delete sounds exactly the same, costs less, you can put custom tips on, and you eliminate a ton of weight and the ugly stock look.

Dude, you got the different exhaust mod's mixed up.

Watch this video below:

The OP did the same mod as the Black M3 and only replaced the 2-pipes inside the center section of the exhaust.

The White M3 replaced 4 pipes which included 2 sections of piping on the left most and right most sections of the exhaust.

Both are OEM exhaust mods and they sound VERY different.

The White car would sound very much like a muffler delete, but the Black car sounds NOTHING like a muffler delete.

I don't know how many times people have to post this!!! LOL

- KJ

[NOTFA5T]

Here is a link to mine done about three months ago.

[tibra1]

Originally Posted by KJ

Dude, you got the different exhaust mod's mixed up.

The OP did the same mod as the Black M3 and only replaced the 2-pipes inside the center section of the exhaust.

The White M3 replaced 4 pipes which included 2 sections of piping on the left most and right most sections of the exhaust.

Both are OEM exhaust mods and they sound VERY different.

The White car would sound very much like a muffler delete, but the Black car sounds NOTHING like a muffler delete.

I don't know how many times people have to post this!!! LOL
- KJ

Totally agree..if you are going to replace all 4 pipes or do the bypass mod your are defeating the helmholtz chamber completely and what you end up with essentially is a straight pipe setup..

By replacing just the 2 pipes in the center you are still maintaining the helmholtz through the 2 smaller steel wool wrapped pipes..this is IMO is the best sounding...anything else you get drone and rasp

[Robmaster]

Originally Posted by Raptor251

You only get a little sound gain, no performance gain and you still have the ugly stock muffler can with the hideous OEM tips...

you also can change the tips






i know, you still have the "ugly" muffler, but for me it's not ugly, i like the muffler.

but the sound with the exhaust mod is soooo great! best mod ever!!

[EliteM3]

Hmmm, that I did not know.

My understanding was that the ACM method bypasses the inner chambers altogether which is in effect a straight pipe mod.

The two perforated pipes are located in opposite inner chambers, but the are also connected to the shorter perf pipes wrapped in Steel wool.

I did not realize that the shorter perf portion of the inner chambers were considered the hemholtz chamber.

If that is the case, stick with replacing ONLY the larger perforated sections of pipe. No drone and truly awesome sound.

In all seriousness, Aftermarket exhaust manufacturers would not have a business on E9x M3 exhausts if BMW did this from the factory by default.

It is amazing. It sounds better every day. I drive with the windows down as much as I can. Do it and you will NOT be disappointed.

[sjuang]

Anyone know of a good place I can get this done in the san Jose/mountain view area.

[Da M3nace]

I had this done with ACM and am very satisfied. I posted only notable drawbacks are very loud, almost annoying cold starts and power band at low rpm seems a little stretched. Low end rpm does not feel quite as torquie. This could be just loudness of exhaust at lower rpms affecting my senses. Anyone else notice these things?

[M3Denver]

im guessing this is pure sound difference and zero performance gains?

[tibra1]

Originally Posted by M3Denver

im guessing this is pure sound difference and zero performance gains?

I wouldnt say zero, minimial is a better description....you are still allowing exhaust gases to escape quicker..

[M3Denver]

Originally Posted by tibra1

I wouldnt say zero, minimial is a better description....you are still allowing exhaust gases to escape quicker..

fair point.... by zero i mean, .5 hp and .2 tq

[DARK_M3]

Originally Posted by tibra1

No power gains..purely sound ..best $400 I have spent on the car..I have #1

CLICK

1. Replaced 2 Long perforated pipes w/ straight pipes

2. Replaced all 4 perforated pipes with straight pipes

Yikes!

Best $0 I ever spent... I did it myself and didn't even have to remove the exhaust from the car.

The deep V8 sound is glorious with all that fiberglass or steel "stuffing" out.

[tibra1]

Originally Posted by DARK_M3

Yikes!

Best $0 I ever spent... I did it myself and didn't even have to remove the exhaust from the car.

The deep V8 sound is glorious with all that fiberglass or steel "stuffing" out.

$400 all in including purchase of a used OEM to cut up and installation isnt that bad (I kept my original stock exhaust)

Never heard of what you talk about but if you like it then