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Discussion Starter · #1 ·
I looked through the tail pipes of my stock muffler a week or so back and discovered that our stock mufflers are already a straight through design. I even shoved a garden hose all the way through the left tail pipe (right one is obstructed by the valve).

from what I have gathered, there are at least two different mufflers for rhe 325/330.

so anyway, the 325 comes with a muffler that doesn't have the tail pipe valve or the chrome tips.

the 330 has chrome tips and the tail pipe valve.

at the very least, I believe the sports silencer is a 325 muffler with chrome tips welded on. it's already a straight through design so if the sports muffler is any better than the stock one, it must have larger diameter tubing. for 330 owners with the tail pipe valve, loosing the valve alone should reduce the back pressure slightly. I still feel that there is something more to this muffler though.

in order to take this any further, I'd need to see one of thes mufflers in person and see if the pipes are any bigger.

18-10-0-026-767 - 330 "sports silencer" (listed for all 325/330 except convertible)
 

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31st330i said:
I looked through the tail pipes of my stock muffler a week or so back and discovered that our stock mufflers are already a straight through design. I even shoved a garden hose all the way through the left tail pipe (right one is obstructed by the valve).

from what I have gathered, there are at least two different mufflers for rhe 325/330.

so anyway, the 325 comes with a muffler that doesn't have the tail pipe valve or the chrome tips.

the 330 has chrome tips and the tail pipe valve.

at the very least, I believe the sports silencer is a 325 muffler with chrome tips welded on. it's already a straight through design so if the sports muffler is any better than the stock one, it must have larger diameter tubing. for 330 owners with the tail pipe valve, loosing the valve alone should reduce the back pressure slightly. I still feel that there is something more to this muffler though.

in order to take this any further, I'd need to see one of thes mufflers in person and see if the pipes are any bigger.

18-10-0-026-767 - 330 "sports silencer" (listed for all 325/330 except convertible)
Thanks a lot!! :thumb:

Please keep us updated.

Btw, How much do the Dinan springs lower your car. I want better control in the twisties and already have the sways, but I HATE the slammed look. Can you tell me if your rear wheels are up inside the wheel well? :dunno:

Thanks again.
 

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Actually,...

some 325i's come with chrome tips as well as other 330i chrome treatments. My 325xi wagon came with chrome trim pieces (i.e. exhaust, window trim, kidney grill). Manual xi's also share same make of tranmission (but different model number) as manual 330i's, according to Bentley manual. Not sure aboiut the tail-pipe valve though.
 

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King of Rear Clunks
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Wagons come with all exterior 330 bits (chrome kidney slats, painted hood louver, painted trunk/hatch handle lip, chrome window surrounds) except for the Ti headlight inserts, and the chrome exhaust tips were an on-again off-again thing. I know early MY01 wagons had it, but it was deleted at some point, as mine didn't have it, as well as most other 325iTs I've seen.

And my browsing through the ETK shows that 325xi (and presumably xiT) have the muffler valve that other 325s lack.
 

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Discussion Starter · #7 ·
Re: Re: so here's the latest on the BMW "sport silencer" in the ETK

TD330ci said:
Btw, How much do the Dinan springs lower your car. I want better control in the twisties and already have the sways, but I HATE the slammed look. Can you tell me if your rear wheels are up inside the wheel well? :dunno:
it only lowered the car about 1/8" (measuring from teh center of the roundel on the wheel to the fender lip) which is not even really enough to be noticible. then again, I haven' compared it side by side with another car.
 

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Discussion Starter · #8 ·
Ripsnort said:
Have you guys checked out that BMW trailer in the ETK? That is cool! Would love to own one, but at $6500, I think I'll wait...:)
hehehehe I have a subaru forester eith a trailer hitch for that. ;)
 

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Discussion Starter · #9 ·
Kaz said:
Wagons come with all exterior 330 bits (chrome kidney slats, painted hood louver, painted trunk/hatch handle lip, chrome window surrounds) except for the Ti headlight inserts, and the chrome exhaust tips were an on-again off-again thing. I know early MY01 wagons had it, but it was deleted at some point, as mine didn't have it, as well as most other 325iTs I've seen.

And my browsing through the ETK shows that 325xi (and presumably xiT) have the muffler valve that other 325s lack.
the ETK shows one part number for 325 cars up to 9/01 and a different part number for cars produced after 9/01.
 

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Discussion Starter · #10 ·
Kaz said:
Wagons come with all exterior 330 bits (chrome kidney slats, painted hood louver, painted trunk/hatch handle lip, chrome window surrounds) except for the Ti headlight inserts, and the chrome exhaust tips were an on-again off-again thing. I know early MY01 wagons had it, but it was deleted at some point, as mine didn't have it, as well as most other 325iTs I've seen.

And my browsing through the ETK shows that 325xi (and presumably xiT) have the muffler valve that other 325s lack.
Kaz: I saw an alpine white 2002 kaz-movile on the highway today. it looked pretty good. :)
 

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31st330i said:


Kaz: I saw an alpine white 2002 kaz-movile on the highway today. it looked pretty good. :)
[/QUOTE

I've yet to see an 02 wagon. I want to see how the taillights look, as I've seen 3 different photos and they all look different. I wanna see if I can swap out the bulb holder and get it to light up like a E39 wagon. :D
 

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The Original Dr. Phil
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Kaz said:
31st330i said:


Kaz: I saw an alpine white 2002 kaz-movile on the highway today. it looked pretty good. :)
[/QUOTE

I've yet to see an 02 wagon. I want to see how the taillights look, as I've seen 3 different photos and they all look different. I wanna see if I can swap out the bulb holder and get it to light up like a E39 wagon. :D
Maybe this pic can help, its an 02. Close up in my signature if you have em turned off.


If you want to see them in larger format, open the properties and add .orig.jpg to the address and you can see them better.
 

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FWIW, my salesman said the 330 exhaust was designed in a wind tunnel. Don't know if it's possible to improve on perfection.:angel: I like the sound of my 02 330 exhaust.
 

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Discussion Starter · #15 ·
agreed, the stock muffler is pretty good and i like the way it sounds as well. I'm hoping this optional OEM muffler is even better but I may end up throwing in the towel on this project if I can't verify that the sports muffler is any better.
 

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The way a straight through muffler works is: The pipe inside the muffler housing is perforated at the inlet end and since even a straight pipe has some backpressure, some of the exhaust gases pass through the perfs. They then travel through a series of baffles and rejoin the gases in the pipe through additional perforations toward the exit side of the muffler. they are now out-of-phase with the main flow and this is what create a degree of backpressure since the out-of-phase flow is putting the brakes on the total flow. It also reduces noise. I would assume the Sport Muffler has a different perf and baffle setup. A larger diameter inside pipe would not help if the exit pipes are the same diameter as the stock muffler.
 

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Discussion Starter · #17 ·
thanks for the tidbit. that explains some of the cutaway pictures I've seen where the OEM muffler is actually a stack of perforated tubes welded together.

so what does say about aftermarket mufflers which are essentially just perforate pipes through a packed can. except for maybe supersprint, I don't think there's any sort of bafeling outside of the perforated tubing. the only differences that I can tell then are the length and diameter of the muffler can itself.
 

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I think you're right - most of the aftermarket performance mufflers probably have no baffling - that's why they're usually a little louder. Sometimes it's hard to tell the difference until you run into the natural resonance range of the engine - then some of the exhausts can drive you nuts - especially if it occurs near cruising speed. The factory engineers spend hours tuning out these "hot spots."

I know the 1960's Porsche 911 factory sports muffler just had a few less baffles. Even better, it had a side outlet like the stock exhaust for street driving and two flanged, pretty much unsilenced outlets with threaded cap-off plates you could remove for track days!
 

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Discussion Starter · #19 · (Edited)
short of just taking a chance and ordering one, I don't know what to think. I emailed BMWNA through the owner's circle and they simply replied with "...ask the service manager at your local dealership...."

owner's circle has not been able to answer any question I've sent in and they bungled my steering retrofit and caused me to wait like 6 months in total from first being "put on the list" until time of actual installation. what a complete waste of time, that site.
 
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