In search of the quietest 1M exhaust...

[ozinaldo]

Originally Posted by jackkk

Do you have drone with your set up?
I got the SS sport and stock mids, so I got some metallic drone around 1500RPM, but I think it is because of bad instalation of the exhaust, because when listening the music with hard bass(logic 7) I hear some bad metallic voice from the same place

I have nothing like that, seems like bad install to me as well. I have a minimal drone at a very narrow band between 2200 to 2400 but nothing like the stock drone, it is even likeable and I assume it is going to be better with more mileage.

[jackkk]

Originally Posted by ozinaldo

I have nothing like that, seems like bad install to me as well. I have a minimal drone at a very narrow band between 2200 to 2400 but nothing like the stock drone, it is even likeable and I assume it is going to be better with more mileage.

looking for somethink with no drone at all) And you run the stock map? I plan to go with Evolve st1

[bvez3ro]

My Eisenmann Sport Exhaust came today. Have to make an appointment at my dealer to put it on. I will check if the drone is still there, cuz everything is stock except the Axle back Eisenmann Exhaust.

[beemer]

n55 mids completely eliminated the drone in my car.

[Artemis]

Replacing the N54 mids by the N55 mids on the 1M = significant reduction of 'drone'.

See these threads:
http://www.1addicts.com/forums/showthread.php?t=651547
http://www.1addicts.com/forums/showthread.php?t=662265
http://www.1addicts.com/forums/showthread.php?t=709182
http://www.1addicts.com/forums/showthread.php?t=677414

Benefits of N55 mids on the 1M:

• BMW OEM part;
• easy plug and play / bolt-on install (same shape and connections) and ditto removal (if ever required to);
• cheap mod for what you get in return: normal price is sub $400 (call around because prices seem to range - BMW OEM part, so your BMW dealer can certainly get them for you);
• significant reduction of drone;
• a little extra growl on the sound spectrum (if you want a louder, raspier noise, get Maddad mids instead of N55 mids);
• less restricted fumes flow (due to the absence of secondary cats) - a little extra oomph (few extra hp);
• ECU will not throw codes at you (reason: primary cats and sensors are sitting in the downpipes connected to the mids); only if you go for catless downpipes (loud !), the ECU will protest and, hence, needs to be reprogrammed (which voids the warranty);
• no undesirable results (too loud, too smelly, risk of trouble with authorities and neighbors)

N55 mids = BMW OEM part # 18307599743
For the OEM bolts and gaskets part #, see these earlier posts of Dackel:
http://www.1addicts.com/forums/showp...02&postcount=8
http://www.1addicts.com/forums/showp...1&postcount=16

In the event of replacing the N54 mids by the N55 mids, definitely keep the N54 mids somewhere for possible future re-install (1M resale). As a matter of fact, due to the presence of secondary cats, the N54 mids are ± five times more expensive than the N55 mids !

N55 midpipes (left - no secondary cats) versus N54 midpipes (right - secondary cats):

[-Z-]

Originally Posted by Artemis

N55 midpipes (left - no secondary cats) versus N54 midpipes (right - secondary cats):
Attachment 810958

as we all know by now, 1M mid pipe is not an ordinary N54 mid pipe, and does not have any cats.

[ozinaldo]

Originally Posted by -Z-

as we all know by now, 1M mid pipe is not an ordinary N54 mid pipe, and does not have any cats.

I think you got it wrong. Yes it is not ordinary N54 mid pipe but 1M mid pipes do have cats, the resonator on the other hand turns out to be a dummy.

[-Z-]

Originally Posted by ozinaldo

I think you got it wrong. Yes it is not ordinary N54 mid pipe but 1M mid pipes do have cats, the resonator on the other hand turns out to be a dummy.

you right. Got it confused, although I thought I had seen it somewhere those cats cut open and they were faked just like the muffler part.

Still think N55 mid is a waste, but the good thing it's very cheep, lightly used sells for around $250.

[Artemis]

Originally Posted by -Z-

as we all know by now, 1M mid pipe is not an ordinary N54 mid pipe, and does not have any cats.

Please elaborate.

If those dangly bits on the N54 mids of the 1M are no secondary cats (see the red circle in the picture below), then what are these according to you and why do those N54 mids are ± five times as expensive as N55 mids ?

As Oz pointed out, aren't you confusing with the resonator ?
see http://www.1addicts.com/forums/showthread.php?t=779462

[Artemis]

Originally Posted by -Z-

N55 pipe is a waste of money, imho

I respect your point of view - to each his own.

The proof of the pudding is in the eating: experiences in the threads referenced above in post #27 shed another light, though.

Maddad mids are situated in a different price and sound range than the N55 mids.

[Artemis]

Replacement of the N54 midpipe by the N55 midpipe (DIY installation process):
http://www.1addicts.com/forums/showthread.php?t=797160