525i exhaust and exploration of some very specific options

[ghostbutts]

I know the topic has been covered before but I'm not finding what I am looking for. Posting in the touring forum because to me the sedan is a totally different beast and the cabin is more insulated from noise as opposed to the touring cabin.

in short: what I'm looking for is a bit more growl without adding drone.

The original configuration was stock exhaust with the giant single muffler with the straight tip. I didnt like how quiet it was so the first experiment was a muffler delete. I really liked how the car sounded with no muffler and kept it for a while, but I got pretty annoyed with a drone that i was getting somewhere between 1800 and 2200 rpm iirc. I should also mention that at this point I used Noico 80mil sound deadening mats to cover most of the wheel well.

The next experiment and current set up was adding a magnaflow straight through model 11236. It got rid of the drone, but definitely quieted everything down. To me, it sounds pretty decent accelerating on the highway, but still seems pretty tame otherwise.

Now I am looking at trying a few different options.

1) Y resonator delete and replace with straight pipe.
->My guess: drone city.

2) Y-res delete, replace with glass pack? replace with something else?
-> I've never used a glass pack before so I dont know what to expect.

3) Y-res delete, replace with straight pipe. Remove the magnaflow muffler and replace with scuba tank from 540.
->At some point i drove a wagon in which precisely this was done according the owner. I only got to drive it around a neighborhood so I have no idea what it was like through out the range but it sounded nice. I am kind of leaning toward this, my logic being that a scuba tank muffler designed for a 540 is supposed to quiet down the exhaust through a secondary resonator for the larger V8 engine after exhaust already passes through Y-res. In my case, since this is I6, if drone increases from removing the Y-res and going straight piple, this should be offset by the scuba tank... Not super excited about adding this massive heavy muffler to the system, but I suppose at least that's offset if the Y-res is gone.

What do you guys think? In terms of cost, I already have the scuba tank (picked up for free from a 540 owner), so in terms of least to most expensive would be to remove the Y-res, replace with a pipe, drive around for a bit and if it sounds bad/drones, which i am guessing it will, I then proceed to the scuba tank experiment. If that sounds bad, I add a glasspack where the Y-res was, or something else? If I'm still getting drone, will doing another layer of dynamat on all metal surfaces in the trunk / wheel well help, followed up by MLV rubber?

At that point if its still bad, I go back to the original system. Hopefully I dont have to go through every combination to get to where I want to be.

[adm750]

man...I have no clue...but am looking forward to seeing what gets posted.

I would like to open mine up a bit but am not quite sure where to start. Sounds like you have the M-tech bumper ? I thought about straight-piping mine (removing muffler..) but sounds like that may not be the way to go since I spend a bit of time in that RPM range...

How quiet is the magnaflow ?? Good tone just not enough bark for you ? (might be interested in that muffler if you wind up having a fire sale...lol...)

Like I said...looking forward to seeing what get's posted up...

[ghostbutts]

The magnaflow is decent performance muffler. Could be louder.

[Plattus1000]

Keep your resonator, it helps to reduce drone. Drop the scuba tank and get a larger diameter muffler? (lower tone)

Swap in a V8?

A friend with a diesel audi paid for some electronic gizmo that simulates a deep exhaust sound through his stereo. It's amusing but disgusting at the same time.

[FieroSS]

How long have you had the Magnaflow on the car? Mine got louder with miles.

My 528i was completely stock and i replaced ONLY the stock muffler with the Magnaflow 14815 dual tip muffler. On first start up it was NO louder and I was NOT happy. After quite a bit of driving it got a fair amount louder but had NO drone and i'm satisfied with it. I would like more noise but I fear any of the options you are talking about would give me drone and take a decent amount of work so I'll probably leave it.

I always wished I would have tried it with no muffler at all but if you experienced drone it puts my mind at ease.

-Tim

[JaxPlanet]

IMHO: If you don't want drone, don't delete anything. The key is replacing the final resonator/muffler with something that plays a tune you enjoy. Be ready to drop around $300+ for a stainless steel concerto. Dinan, Borla, Billy Boat, Super Sprint, Remus, all play different tunes. Go to YouTube.com and find samples of what these sound like but make sure the samples are for an i6, not a v8.

[ghostbutts]

I thought about straight-piping mine (removing muffler..) but sounds like that may not be the way to go since I spend a bit of time in that RPM range...

I was not happy with that set up and today was reminded why.

Today I went to the shop (Kwik Way in San Jose) and the owner convinced me that my idea of straight-piping the Y-res and replacing my magnaflow with the scuba tank would end up in the same result of the original muffler delete.

We removed the front resonator instead and tested it with dual straight pipe. The exhaust note improved but again, I noticed drone/cabin noise when accelerating between 1900-2500 RPM and I wasnt having it. Everything in the range sounded great, except that narrow band where I know that if I were cruising in the mountains it would annoy me to hell.

We put in a X-pipe instead and so far so good. Tone is a little more aggressive and so far I'm not noticing any *significant* cabin noise. Will see how it is after some more "testing."

Current set up: stock cats -> front res removed and replaced with X-pipe -> Y-res -> Magnaflow 11236.

[ghostbutts]

I think the resonator is going back on tomorrow. Still have cabin noise. Seems like I cant have my cake and eat it too....

[adm750]

I think the resonator is going back on tomorrow. Still have cabin noise. Seems like I cant have my cake and eat it too....

hmmm....sounds exhausting Ghost....

ok, that was a really stupid pun...but I can't believe I'm the first one to say it.

Any chance you can re-mount that (what looks to be) large rubber damper onto the pipe near the muffler ?? I wonder if that would tame the vibrations creating the resonance ? Cut the bracket off the scuba tank inlet and either make a new one with ears and clamp it to the pipe, or have the muffler shop re-weld it.... I'm thinking that re-welding the original bracket would probably provide the best vibration absorption...

[ghostbutts]

^interesting thought, how far up before the muffler are you thinking this would be added? same-ish location as stock?

In the same category, I noticed that on the part of the Y-res that is closed off, there is a rod that looks like it could/would be a place for a damper. Anyone know what this is for?

https://www.dropbox.com/s/nou5r6avne...%2012%2012.jpg

[adm750]

^^^ I dunno ghost....but I was thinking somewhere like you said...in the stock-ish location....at the end, near the muffler.

I do see the rod you are talking about in the dropbox photo...and when I search res pix online, it shows it on some resonators and not others. Could simply be a different hanger...but honestly not sure what that is for....