What's Inside an OE Muffler?

[Incompatible]

Has anyone opened up a factory muffler (back box) and looled inside? I'm curious why these are 1. so heavy and 2. if they use a baffle or packing design?

[3002 tii]

I've seen few posts from you on the topic of resonator, muffler, exhaust etc. It seems not many have experimented with going the custom route or messing with the stocker so unfortunately seems like only way you'll getyour answer is to be the guinea pig.

FYI I recall reading somewhere that the Dinan muffler is essentially a stock muffler that's been gutted?

[Incompatible]

Originally Posted by Dubbedown

I've seen few posts from you on the topic of resonator, muffler, exhaust etc. It seems not many have experimented with going the custom route or messing with the stocker so unfortunately seems like only way you'll getyour answer is to be the guinea pig.

Starting to look like that's the way things will go. Just trying to come up to speed after being away from performance cars for 20+ years. There has been a number of design/concept changes. I really don't want to start spending money I don't have to or cutting on a car which is still relatively new unless I know what I'm doing. Big advantage having the experience and knowledge of others on these forums.

Originally Posted by Dubbedown

FYI I recall reading somewhere that the Dinan muffler is essentially a stock muffler that's been gutted?

Dinan probably has done a finese job of this, but it does seem that way. BMW has done a lot of work to make these flow well, sound decent, and be quiet to comply with the various sound level regulations. Maybe a bit of internal work..... Now to find a oe can for cheap.

[3002 tii]

honesty, if i could've gone custom (found a good reputable shop nearby), i would've done the same. but since there was none around me i just shelled out the money for a complete system. after having to go through trial and error with few systems, the one thing i learned end of day is that the stocker isn't that bad. some of my "errors" involved putting on some really loud systems with too much drone. i then appreciated the stock system - quiet enough where ride quality isn't sacrificed but still has enough of a low rumble to differentiate itself from others. 2 of my good friends both drove an e46 m3 before trading to their current whip and i recall both being impressed with the stock system.

why not just go simplest/cheapest in terms of order of mods.

first start off with mid resonator, run straight pipe into stock muffler. if too loud, go no further and put on a glasspack. and if too quiet, work your way down to the muffler?

[Incompatible]

Originally Posted by Dubbedown

honesty, if i could've gone custom (found a good reputable shop nearby), i would've done the same. but since there was none around me i just shelled out the money for a complete system. after having to go through trial and error with few systems, the one thing i learned end of day is that the stocker isn't that bad. some of my "errors" involved putting on some really loud systems with too much drone. i then appreciated the stock system - quiet enough where ride quality isn't sacrificed but still has enough of a low rumble to differentiate itself from others. 2 of my good friends both drove an e46 m3 before trading to their current whip and i recall both being impressed with the stock system.

why not just go simplest/cheapest in terms of order of mods.

first start off with mid resonator, run straight pipe into stock muffler. if too loud, go no further and put on a glasspack. and if too quiet, work your way down to the muffler?

I do appreciate what the oe system has to offer, but I would like a little bit "more" if I can without spending a lot or hurting performance. My concern with starting off with the resonators is that being in a state which is very aggressive about emission/exhaust mods, I can't nail down exactly what our resonators/secondary catalysts truely are. Going by BMW nomenclature in the parts listing they're cats. You've probably seen my posts for a resonator delete.

Part of the fun is doing the research and if it looks promising, the experimenting. BTW I've followed your posts about your exhaust experiences and have found them to be helpful.

[Matty C]

Originally Posted by Incompatible

I do appreciate what the oe system has to offer, but I would like a little bit "more" if I can without spending a lot or hurting performance.

Take a look at the Eisenmann Sport. You can deal directly with the factory in Germany and they will give you a sweet deal. They will also ship tax free to the States.

[ZED4Mjjl]

The mid resonators on the Z4M are exactly that and not cats I was told by a dealership mechanic that the confusion stems from the cats being built into the headers for US versions. The Euro versions have the cats where our resonators are. Hope that helps.

[Incompatible]

Originally Posted by ZED4Mjjl

The mid resonators on the Z4M are exactly that and not cats I was told by a dealership mechanic that the confusion stems from the cats being built into the headers for US versions. The Euro versions have the cats where our resonators are. Hope that helps.

Thanks for the info. What you were told sounds reasonable, but I'll demonstrate some of the reason for the uncertainty. The following is from realOEM.com

US Z4 3.0Si, 5/07 build, left hand drive:
02 Rmfd exhaust pipe with catalyt.converter ZYL. 1-6 18307562227

Euro Z4 3.0SI, 5/07 build, left hand drive:
01 Exhaust pipes with primary silencer 18107547103

Part 02 for US cars is identified as a catalyst and looks like what I have under my car. Part 01 for Euro spec cars is identified as a silencer and does not look like what I have under the car.

I have been told that the US cars have the catalysts as part of the exhaust manifolds and the Euro cars do not. With that reasoning, the 02 part should be on the Euro cars and not the US cars. (If the parts diagram is correct for it's numbering/nomenclature.) To add to that, many here in the US have reported doing resonator deletes or "Cat back" systems without any problems with emissions testing. Being in Kalifornia, I haven't talked to anyone with an Si car who has done a delete/system and gone thorough the state's emissions test.

Lastly, those inline twin cylinders on our cars sure resemble some of the aftermarket catalysts.

Thanks again for the post, sooner or later I hope to track this down.