[DYOOS]

I recently got the PE mod done to my N55 335i. Right now, I'm basically all stock with a PE mod. I eventually plan on being FBO with catback dps + MHD/XHP tune. I'm happy with the overall sound of the PE mod, but the drone is kind of giving me a headache.

I noticed that my vacuum line that's hooked up to the driver side muffler/actuator is missing. Does having this plugged back in make a difference with drone?

As an alternative, I'm thinking of adding more muffler packaging/insulation inside the muffler to help decrease the drone. Has anyone tried adding 2x or 3x more muffler packaging/insulation to help quiet the in-cabin drone?

I've also read that 1790 vibration resonator can help and that some ppl when adding catback dps have experienced less drone.

[maddmatth]

Originally Posted by DYOOS

I noticed that my vacuum line that's hooked up to the driver side muffler/actuator is missing. Does having this plugged back in make a difference with drone?

Yes, think this is your problem. I did not get drone with the PE mod, I kept the flap hooked up.
I only felt the need for resonators when I went catless, because that doubled the volume...

[DYOOS]

Originally Posted by maddmatth

Yes, think this is your problem. I did not get drone with the PE mod, I kept the flap hooked up.
I only felt the need for resonators when I went catless, because that doubled the volume...

Thing is I replaced the resonator in the driver side muffler with a straight pipe. Does hooking up the vacuum line even make a difference at this point since it's main purpose was to keep the flap closed at certain RPMs?

[maddmatth]

Originally Posted by DYOOS

Thing is I replaced the resonator in the driver side muffler with a straight pipe. Does hooking up the vacuum line even make a difference at this point since it's main purpose was to keep the flap closed at certain RPMs?

So did I. Yep it does as long as the inner pipes are still perforated. It closes when the car is cruising which helps a bit. I don't notice any drone when cruising.

[DYOOS]

Originally Posted by maddmatth

So did I. Yep it does as long as the inner pipes are still perforated. It closes when the car is cruising which helps a bit. I don't notice any drone when cruising.

This absolutely solved all my problems. The person who did my PE mod must have detached the vacuum line since it was tucked away with a screw in it. Figured he thought I'd want a louder note.

I was able to find the vacuum line and re-plug it. Basically no drone any more!!!

[DYOOS]

Wanted to revive this thread because I got catted downpipes installed along with my PE mod, and there is a bit more drone. Is it possible to decrease the drone instead of driving in manual and shifting early every time?

[maddmatth]

The Vibrant resonators will help with that. The cat kinda acts as a resonator so resonators will make up for removing it (or replacing it with a race cat).

[DYOOS]

Originally Posted by maddmatth

The Vibrant resonators will help with that. The cat kinda acts as a resonator so resonators will make up for removing it (or replacing it with a race cat).

On an N55 exhaust, do you just put vibrant resonators anywhere you can fit them throughout the piping?

[maddmatth]

Originally Posted by DYOOS

On an N55 exhaust, do you just put vibrant resonators anywhere you can fit them throughout the piping?

Yep. There's a nice spot for them about in the middle under a heat shield, where the X-drive/sedan/N54 versions would have their secondary cats, where they fit perfectly.

[DYOOS]

Originally Posted by maddmatth

Yep. There's a nice spot for them about in the middle under a heat shield, where the X-drive/sedan/N54 versions would have their secondary cats, where they fit perfectly.

Have you installed the vibrant resonators yourself? I've been reading reviews that it has worked and one lengthy post that it doesn't.

I'm also reading that 1790 is for OEM exhaust pipes, which are 2.25" in diameter. 1792 is for 2.5" in diameter. Which one would work for N55 E90? I'm thinking the 1790 since it'll be a more seamless fit.

[maddmatth]

Yes. Catless, PE mod, and a pair of Vibrant resonators. There's another thread around here with sound clips from someone with the same setup.
I like it, nice balance of good sound without being too obnoxious.
It's a slightly deeper sound than PE with the stock cat but similar volume, maybe a tad louder. The burbles and crackles are louder.

[DYOOS]

Originally Posted by maddmatth

Yes. Catless, PE mod, and a pair of Vibrant resonators. There's another thread around here with sound clips from someone with the same setup.
I like it, nice balance of good sound without being too obnoxious.
It's a slightly deeper sound than PE with the stock cat but similar volume, maybe a tad louder. The burbles and crackles are louder.

Thanks for the feedback man - appreciate it. Need to look into adding these. I only had the droning issue when I put the catted downpipes. Without the catted downpipe I had no drone with the PE mod.

[DYOOS]

Found out about Vibrant 1141 2.5" Ultra Quiet Resonators. I'd like to add these on my E90 N55. These look bigger than Vibrant 1792 width wise. Would the Vibrant 1141 fit on my exhaust under the heat shield?