M3 exhaust modification

[DirtyJersey]

Originally Posted by Stainless 45

This is exactly what I did, and to me the sound is perfect.

Sweet!

[HP Man]

Originally Posted by Stainless 45

My welder tig welded the cans shut, they are single layer.

The cans are double-walled, not single.

[kcdude24]

Originally Posted by Yoyoman

Hey Bubbles:

Called BMW Morristown today and asked for Michael N. They didn't know what I was talking about, not sure who Michael N was. Do you have any contact info for Michael that I can get in contact with? You can PM me

thank you,

Ask them who manages their ebay auctions...see if that person can see if there are any laying around.

[F82_SID]

I just did mine yesterday! I absolutely love the sound! Its perfect for the price. The shop thought it would be easier and give the same result to just weld a pipe over the perforated ones instead of cutting them all the way off. I have to say, I think they were right and that is the better way to go.

[llis]

Originally Posted by E92_SID

I just did mine yesterday! I absolutely love the sound! Its perfect for the price. The shop thought it would be easier and give the same result to just weld a pipe over the perforated ones instead of cutting them all the way off. I have to say, I think they were right and that is the better way to go.

I look forward to hearing it IRL! (Any local M3 drives planned? I'll miss the Euroberge, going to HPR next weekend.)

[JCtx]

Originally Posted by E92_SID

I just did mine yesterday! I absolutely love the sound!

Hey man, a word of advice: CHECK THE TORQUE OF YOUR DIFFERENTIAL BOLTS!!! You shop, like most others, removed the differential bolts to drop the exhaust with the brackets still attached (your pics provided the evidence ). If not torqued properly, that can lead to a broken rear subframe and differential failure. Don't become another statistic .

And yes, a 'sleeve' is the best way to do the job. Several others have done it that way, if you search. Wish somebody local could do that job. Hey, could you ask the shop what did they use? Just curious.

[Stainless 45]

Originally Posted by HP Man

The cans are double-walled, not single.

I cut mine open with an angle grinder and I can definitely tell you that at least on a 2011 the chambers are single walled. There may be a crimp or overlap where the chambers separate, but the sections cut out in the above pics are 1 layer of SS.

[snowmants]

Finally got mine back from the welder. They only welded the cans shut for me. I covered the perforated pipes myself with exhaust clamps(pictures on the previous page of this thread). The sound is awesome! This is how the car should have come from the factory. No drone at all, but you a get a more aggressive sound when you get on the throttle or blip the down shift. It sounds fantastic. Sounds much more exotic. The car goes from a growl to a scream as you get higher in the rpm range. As everyone else has already said in this thread DO THIS MOD. You will not be sorry. I will post some video shortly as I believe I am the first to use the exhaust clamp method, but I don't think there is much difference, if any, in sound from the others already posted in this thread.

[snowmants]

[F82_SID]

Originally Posted by elp_jc

Hey man, a word of advice: CHECK THE TORQUE OF YOUR DIFFERENTIAL BOLTS!!! You shop, like most others, removed the differential bolts to drop the exhaust with the brackets still attached (your pics provided the evidence ). If not torqued properly, that can lead to a broken rear subframe and differential failure. Don't become another statistic .

And yes, a 'sleeve' is the best way to do the job. Several others have done it that way, if you search. Wish somebody local could do that job. Hey, could you ask the shop what did they use? Just curious.

Ask them what they used? You mean what size of pipe?

Also, where are the differential bolts that I need to check? Can you point out where they would go in the pict? How can I make sure they are torqued properly?

[Bubbles]

Came back from the track this past weekend. When an Akra owner, Dinan owner and BMW performance exhaust owner ask you what exhaust you are running after checking out the stock muffler, you know it sounds great. Add in several GT3 owners, a Lambo owner and Ferrari owner you know you have a winner.

I had several drivers at the track ask me what I had done to the motor.

I caught several peeking under my car between track sessions.

As someone has already stated, the car growls at low rpm and screams at higher rpm. Rev matching sounds terrific.

On a side note, the volume has made it easier to rev match shifts. My porsche buddies were green with envy with the V8 note.

Caveat: It is very loud on cold start.

[HP Man]

Originally Posted by Stainless 45

I cut mine open with an angle grinder and I can definitely tell you that at least on a 2011 the chambers are single walled. There may be a crimp or overlap where the chambers separate, but the sections cut out in the above pics are 1 layer of SS.

Strange -- I have an exhaust from a 2008 and they are definitely double walled.

[JCtx]

Originally Posted by E92_SID

Ask them what they used? You mean what size of pipe?

Just ask them details on what they used. They might have used pipe, or just sheetmetal. It'd be nice to know gauge, size, and where they bought it.

Just look at the pictures you posted, and you'll clearly see the brackets near the flange at the end of the connecting pipes. Those brackets are held by TWO OUT OF THREE differential bolts. It's critical they were torqued properly, as several folks have lost the diff due to loose (or missing) bolts. And no, I don't know the correct torque value; maybe somebody can post it .

[F82_SID]

The video is in from my exhaust mod! Thanks to Andrew at AR Design!

[snowmants]

Originally Posted by HP Man

Strange -- I have an exhaust from a 2008 and they are definitely double walled.

They must have changed the design. Although my car is an '08 I bought a muffler from a guy with a 2011 to do this mod and it was single walled. so somewhere along the line the design must have changed from double to single.

[snowmants]

Finally! I got a video of my modified exhaust. I am the one who used the exhaust clamps over the 2 large perforated pipes only (pictures in the previous 2 pages of this thread). I left the steel wool on the other 2 pipes and packed all of the fiberglass stuffing back into the muffler before it was welded shut again.

[F82_SID]

That sounds awesome man! This is by far the best mod that I have done to my car!

[kcdude24]

Nice! You need to post up a long term report on how the clamps hold up.

[snowmants]

Originally Posted by kcdude24

Nice! You need to post up a long term report on how the clamps hold up.

Will do!

[bigjae1976]

I wish I would have known about this when I was at Active Autowerke in Jun...they had almost 20 stock exhausts just sitting there taking up space. I am 99% sure they would have given me one or five if I asked.

[Tomislav]

its how it should sound straight out of the factory, definitely on my list of things to do.

[snowmants]

Originally Posted by Tomislav

its how it should sound straight out of the factory, definitely on my list of things to do.

That was exactly what I said the first time i cranked the m3 up after installing the modified exhaust. I cant believe BMW didnt sell the car this way! Windows shut, cruising on the highway, it is just as quiet as stock. It is really only on cold start and when you get into the throttle that it sounds different.