[StevenY.]

Originally Posted by Sered

Yes, it would. Soundwaves, like lightwaves; when absorbed by a medium are then generally re-emitted by that medium as a new source. For soundwaves, this effect is most prevalent in what's commonly called 'droning' and generally requires lower freqs to do it.

So long as the packing is there, it is NOT a muffler delete. Will it be as loud as one? Almost I'm sure, but alot of the nasty rasp and drone that was previously absorbed by the mufflers will still be absorbed, just to a smaller degree.

Furthermore, wrapping the perf pipes with header-wrap will allow some sound through. More than solid pipes.

On topic: I'm still waiting for videos. I ALMOST got this done this weekend, but the gf wanted $600 worth of Halloween/Renn-fair costume and I bought a Kegerator for a party Maybe next weekend. If no one else wants to do this, I'll be doing it by next weekend most likely.

Whoa, 600 on costumes??

Anyway, hope to hear from you soon and hope that everything works out!!

[Sered]

Originally Posted by StevenY.

Whoa, 600 on costumes??

Anyway, hope to hear from you soon and hope that everything works out!!

Yeah, she found a set of professional-quality armor 'on-sale'. Oye.

I'm going to attempt to video the exhaust after it's done, but it won't be with a GoPro as I don't have one.

[TommyLights]

Originally Posted by e92ben

Actually I just got the car back from dealer for wastegate & turbos..
So I had to reschedule with the shop Saturday 7:30 am. It's gonna happen lol I'm making sure of this. Saturday afternoon I'm gonna make a full new thread on this

What happened with this?

[e92oholic]

Originally Posted by tomz_335i

What happened with this?

Seems like BMW usa had him killed off. Glad i wasn't first

[StevenY.]

I guess this is a sign that none of us should ever attempt this again or we'll all be taken out by BMW left and right.

[TommyLights]

Ah well. Did mine and very happy with the sound, but it sounds a lot deeper than PE.

[jlcolon2001]

Originally Posted by tomz_335i

Ah well. Did mine and very happy with the sound, but it sounds a lot deeper than PE.

Post a video or it never happened!

[wahooooman]

Originally Posted by jlcolon2001

Post a video or it never happened!

+1

[StevenY.]

Originally Posted by wahooooman

+1

He did, it's a few pages back.

Originally Posted by tomz_335i

https://www.youtube.com/watch?v=Q_1A...e_gdata_player

[Sered]

Keep in mind, his is pretty much a muffler delete, no packing, no perforated pipes.

[FirstBMWLA]

Originally Posted by tomz_335i

https://www.youtube.com/watch?v=Q_1A...e_gdata_player

Sounds good IMO.

Seems about as loud as my downpipes + Eisenmann Race

[Ace_HollyWood]

So i am kinda confused on this thread, did we come up with how to replicate the PE exhaust? Or just do a mode to make it sound like a PE exhaust. Also I am confused on the relationship/difference between muffler delete and this mod. Can someone please explain?

[StevenY.]

Originally Posted by Ace_HollyWood

So i am kinda confused on this thread, did we come up with how to replicate the PE exhaust? Or just do a mode to make it sound like a PE exhaust. Also I am confused on the relationship/difference between muffler delete and this mod. Can someone please explain?

No, no one has replicated the PE exhaust yet but what tomz did is technically a muffler delete. IMO I really like the sound from tomz's mod and seems like there's not much drone at all if you watch the video where tomz takes off.

[TommyLights]

^^Yep, no drone. I was told I should gave some, but there is zero drone. It sounds really good in person, and not at all like a regular muffler delete, which.is what I had on for a week while the muffler was being modified.

My takeaway from doing that was that it looks like the PE sound might be better replicated by just removing some of the packing, maybe half. Pretty happy for now but I might try again in a few months or just spring for a Remus.

[Sered]

Originally Posted by tomz_335i

^^Yep, no drone. I was told I should gave some, but there is zero drone. It sounds really good in person, and not at all like a regular muffler delete, which.is what I had on for a week while the muffler was being modified.

My takeaway from doing that was that it looks like the PE sound might be better replicated by just removing some of the packing, maybe half. Pretty happy for now but I might try again in a few months or just spring for a Remus.

Half-Packing and pipe replacement or no pipe replacement?

[TommyLights]

I would leave the piping intact, at least the H pipe.

[NoTempoLimitN54]

The only way to definitively answer the question about the construction of the BMW Performance exhaust without cutting one open is to have one x-ray'ed.

Are there not large x-ray machines used to inspect aircraft parts for metal fatigue that could work for this.

Yesterday a 335is drive past me while I was waiting to make a left turn (and he's turning left from 90º to my right. He was accelerating quickly so I got a good chance to hear the is exhaust. Then I drove off and heard my own exhaust (stock 335) for comparison.

It seems to me that the sound of the is exhaust had a similar character to stock, except that it was louder and had more of the higher pitched noise.

So maybe it is the same design with less packing...?

[Josh1a1h]

Originally Posted by tomz_335i

I have it on.....mechanic promised me pics later of what he did, but I got a look inside. It sounds siiick. Lots of burbling and crackling without the drone. Sounds very nice when you rev the engine and very similar to a PE exhaust.

He took out all of the insulation and perforated piping, and removed the H pipe, so its basically a straight pipe setup running through the mufflers. For some reason, the addition of the muffler through the pipes eliminates the drone. FWIW, I do have my main cats on, with the secondaries deleted.

Video up later!

After watching the videos, I am impressed! The noise is awesome.
So what was the actual process involved?
Cut it in half and remove all the packing...and re weld?

Cheers

[TommyLights]

Originally Posted by Josh1a1h

After watching the videos, I am impressed! The noise is awesome.
So what was the actual process involved?
Cut it in half and remove all the packing...and re weld?

Cheers

The perforated pipes were replaced with straight piping, and all of the packing was removed. No drone and no buzzing, but loud. It's sound pretty good, video doesnt do it justice. I would however recommend keeping the resonator on the driver side and remove only half of the packing so it sounds a little less loud.

[jlcolon2001]

Originally Posted by NoTempoLimitN54

The only way to definitively answer the question about the construction of the BMW Performance exhaust without cutting one open is to have one x-ray'ed.

Are there not large x-ray machines used to inspect aircraft parts for metal fatigue that could work for this.

Yesterday a 335is drive past me while I was waiting to make a left turn (and he's turning left from 90º to my right. He was accelerating quickly so I got a good chance to hear the is exhaust. Then I drove off and heard my own exhaust (stock 335) for comparison.

It seems to me that the sound of the is exhaust had a similar character to stock, except that it was louder and had more of the higher pitched noise.

So maybe it is the same design with less packing...?

My neighbor has a 335is with catless DPs and it sounds awesome. I haven't heard a 335i with the PE exhaust yet, so I can't compare, but is hard to imagine it can sound better than the 335is exhaust

[NoTempoLimitN54]

Originally Posted by jlcolon2001

My neighbor has a 335is with catless DPs and it sounds awesome. I haven't heard a 335i with the PE exhaust yet, so I can't compare, but is hard to imagine it can sound better than the 335is exhaust

I'm starting to think: Cut the stock mufflers open, wrap the perforated tubes with header wrap, keep the packing material, and weld it shut.

As for the H pipe: The Akrapovic 335i exhaust has an X pipe, which they claim is better than an H pipe. It seems that the H pipe is worth keeping.

So, can anyone recommend a good (and open minded) muffler shop in the Burbank/Glendale CA area?

[Josh1a1h]

Originally Posted by tomz_335i

The perforated pipes were replaced with straight piping, and all of the packing was removed. No drone and no buzzing, but loud. It's sound pretty good, video doesnt do it justice. I would however recommend keeping the resonator on the driver side and remove only half of the packing so it sounds a little less loud.

Cheers for that!

So i will explain to my guy to

Cut in half horizontally
Replace any internal perforated pipes with straight pipes and remove half the packing. edit...i like the idea of wrapping with header wrap, but it may not do the same job?
Do not remove any resonators.

Does this also mean, that you can still make use of the exhaust valve? or does it become rendered useless?

Cheers bud! Thanks for experimenting.