[kujo]

For those with 335is and FULL Cat backs ie: no center cats or resonators

Who has drone ?

6th gear at 2K......

Be honest !!!!!!!!

What system ? How much or how little drone ?
Is it Xpiped ? or divorced ?
No cats with Resonators or Nada ?

kj

[RRGOO7]

glad this thread came up...i wanted to get eisermenn but want to see about drone.....my dads Z06 vette has BB Bullet exhaust and you cant even hear the radio in the car let alone think it drones so bad

[edgarj]

I just had the Eisenmann race (full catback) installed today. I had the segments welded as per Eisenhaus' recommendation. It is sublime in sound and the gains are noticable (w/ Procede) in the upper revs.

I love the sound..... not too loud for my taste, but it has a great depth and really roars at WOT. That said, it drones like hell at ~2K when crusiing at partial throttle. I've only had it for a few hours, so maybe I can live with it if it proves to be managable by avoiding the "drone spot" in daily use. It reminds me of that South Park episode with the "brown note"...... a low frequency sound that when played causes everyone within earshot to experience spontaneous defecatory incontinence. At first I thought it might be amplified by the back seats being folded to accomidate the factory exhaust, but I stored it in the garage and put the seats back up, and the drone remains in full effect. It sounds totally sick in every other circumstance (WOT in the last 2K revs is, by far, the finest sound I've ever experienced), so it will be a shame if the drone forces me to swap for the Meisterschaft (sp?) muffler when it materializes, which is probably going to be a bit less agressive sounding overall.

So, yes, I have drone. The GF is going to love having to shout back and forth on road trips.

Would having the stock resonator spliced in (if possible) the attenuate this effect without killing the note in other ranges? Just a thought.

[boostedbavarian]

great thread..thats why i leaning to more of a softer sounding exhaust.. most gains on the exhaust system will really be made on the downpipes so im not really looking for most gains on the cat back just a good sound.. and if i want to be loud i get in my sti running an rsr turbo back with tial 44mm dump venting to atmosphere...

[Booster]

I installed the Eisenmann full race set-up 2 days ago. The only drone I have is in 4th gear at like 40-45 when the RPM's are at around 2-2.5k... If you are able to shift into 5th at the same speeds (I know, who goes into 5th at 40mph) the drone drops dramatically....

[all8up]

I have a UR exhaust. Which is an exhaust from the downpipe flange and back. Therefore it removes the factory secondary cats (or resonators). The exhaust has an X-pipe and I definitely get drone at around 2k-2700 rpms (not gear dependent).
I went as far as reinstalling the thing since I thought I had a leak.

I have had catback exhausts on many cars before and oddly enough this car has the most drone.

Since it is near impossible to install a resonator anywhere in this exhaust, I am thinking about cutting my factory exhaust to retain those secondary cats and mate it up to the UR exhaust.

[Mr. 5]

Originally Posted by all8up

I have a UR exhaust. Which is an exhaust from the downpipe flange and back. Therefore it removes the factory secondary cats (or resonators). The exhaust has an X-pipe and I definitely get drone at around 2k-2700 rpms (not gear dependent).
I went as far as reinstalling the thing since I thought I had a leak.

I have had catback exhausts on many cars before and oddly enough this car has the most drone.

Since it is near impossible to install a resonator anywhere in this exhaust, I am thinking about cutting my factory exhaust to retain those secondary cats and mate it up to the UR exhaust.

I only purchased the rear section of the UR exhaust because I had a feeling that the drone would be pretty bad. I'm going to use the stock resonator and possibly delete the cats later.
IMO, the drone will disapear with a resonator.

It's getting installed today, and I'll take some pics

[uberschnell]

I installed the UR cat-back exhaust some time ago. First thing I noticed when driving it was the interior drone at around 2K rpm. It was pretty loud. The change in my ashtray was singing, and within a day I started hearing rattling coming from various interior parts. It was especially loud when going up an incline.
I had the stock system reinstalled the next week. It’s amazing how quiet it really is (interior wise).
I got the impression that more then a few people thought I was pussified for doing that. Others say they didn’t have an excessive drone issue or fail to mention the subject when talking about their exhaust mods. Granted, I didn’t weld the connections and I do suspect that it would help, but after playing around with my exhaust, and experiencing other cars with exhaust mods I have come to the conclusion that difference between acceptable and unacceptable drone is more based on a person’s “drone threshold” then it is actual drone levels.
My Drone Threshold is low. I’ve got a sedan, wood trim, leather seats, and my wife will sometimes drive the car. Obviously I not going down the “pure performance” route. I want to try and balance luxury with performance. Hence low “DT”
Others are more interested in creating a pure performance vehicle, hence higher “DT”.

What I’ve learned:
Now, the sound that came out of my car with the UR exhaust was simply amazing. I think most decently designed exhausts will create a wonderful sound on this car. I think you have to work to make it sound bad (CPE fart can???). I also think that you cannot get away from the drone if you want 1) Loud 2) Performance.

I went back and had my stock mufflers replaced with flow through Magnaflow mufflers, keeping the resonator and 2nd cats. Some, but not all of the drone came back. I would say it is about 30% of original drone. I have spoken with a person here who told me that they removed the 2nd cats and that increased drone dramatically.

I opened up the stock mufflers, they are a baffled design (not cheap). From what I have learned that design helps cancel out the low frequencies that cause drone. It is also my understanding that most resonators only cancel out higher frequencies. A resonator that would work on lower frequencies would need to be large enough to catch the larger low freq waves and bounce them back onto themselves, helping cancel them out. Not sure if one would fit since I haven’t found one yet. There are other ways of canceling out low freqs, and if we can find something that does so without introducing too much resistance into the system then that may be the solution.

[gashero]

with my car, I just did the seconday cat delete along with the resonator. I add an xpipe with 2.5 inches pipe all the way to the stock muffler. No drone at any rpm. sound is not as aggressive as most catback with exhaust but is does have a nice note to it that similar to the nissan VQ engine on the FX, 350z, and G35coupe.

[HP Autosport]

Originally Posted by gashero

with my car, I just did the seconday cat delete along with the resonator. I add an xpipe with 2.5 inches pipe all the way to the stock muffler. No drone at any rpm. sound is not as aggressive as most catback with exhaust but is does have a nice note to it that similar to the nissan VQ engine on the FX, 350z, and G35coupe.

Had the Borla Cat-back on our project 335i, no drone so far with ~5000 miles on the system!

I thought most people on this board like it loud with lots of droning?

[kujo]

HP,

Shoot some in car video/sound clips for us.
cruise at 2K r's in 4,5,6th gear, along with the WOT driving shots.

Probably moving to the Borla in the next 2-3 weeks.

kj

[Mr. 5]

I have absolutely no drone!
Check out my clips:

http://www.e90post.com/forums/showpo...78&postcount=1

[Chio]

I have the borla also and it is alittle louder but now much it sounds great!!!!

[Mr. 5]

Originally Posted by Magna3

I have spoken with a person here who told me that they removed the 2nd cats and that increased drone dramatically.

I wonder who you talked to because I don't have it at all. Deleting the secondary cats did absolutely nothing with the noise. I can mention this because I had my exhaust done and then a week later the cats were eliminated and there was no change with the noise.
Now, if you eliminate the resonator then that's a different story.

[uberschnell]

Found that info from someone here. Glad to hear it’s not the case for you.
I'm thinking about replacing the secondary cats with two 12" resonators, plus keep the factory resonator. It should be pretty tame sound wise, but the flow will be much better then stock. It's just after my experience with the UR exhaust I've got drone concerns.

[BHairsto]

Originally Posted by Magna3

Found that info from someone here. Glad to hear it’s not the case for you.
I'm thinking about replacing the secondary cats with two 12" resonators, plus keep the factory resonator. It should be pretty tame sound wise, but the flow will be much better then stock. It's just after my experience with the UR exhaust I've got drone concerns.

What type/model of resonators are you considering, or are they going to be custom built? My UR's drone is absolutley mudering my ears--I took it to a local custom exhaust shop to try to add another muffler or a pair of 4" di. round mufflers (Magnaflow) as resonators, but we could not come up with a solution that would have proper clearances while not impairing my ability to run a lowered suspension setup.

[3thirty5]

Could anyone with RD Sport comment if there's droning or not?

[Walked U]

3 inch dual piping all the way back, with no 2ndary cats or resonator and 4 inch tips.

drone in every gear @ 2-2.5k RPM. after or before that nothing.

Youll get drone in our cars if you take off the 2ndary cats and resonator with aftermarket mufflers.

[Swoop]

Zero Drone from CP-E exhaust and sounds perfect.....I said Peerrrrrrrfect!

[Mr. 5]

Originally Posted by Swoop

Zero Drone from CP-E exhaust and sounds perfect.....I said Peerrrrrrrfect!

Are you serious??
Maybe it's because you are now deaf and just can't hear anything.

[Mr. 5]

Originally Posted by Magna3

Found that info from someone here. Glad to hear it’s not the case for you.
I'm thinking about replacing the secondary cats with two 12" resonators, plus keep the factory resonator. It should be pretty tame sound wise, but the flow will be much better then stock. It's just after my experience with the UR exhaust I've got drone concerns.

Seriously man, I will guarantee that you will have no drone if you just put in straight pipes and no resonators in place of the cats.

I wish you lived a little closer so you can hear what it sounds like in person.
My wife even likes it and that's hard to imagine.
You heard my clips in the car right?

[Swoop]

Uh no....it has no drone.......It has a great sound and it comes off my car tomorrow to begin manufacturing...