[DYOOS]

Been searching through threads to find the exact process of doing the PE mod for an N55 exhaust on an E90, but coming up short.

There seems to be a few different ways you can do the PE mod. I'm looking to doing this mod in the future, but would like to have some knowledge of what exactly is being done to the exhaust for it to be considered a "PE mod". I'm not looking for it to be as loud as possible. I'm more interested in this mod's performance enhancements if slightly any.

[maddmatth]

Basically you're just replacing the outer perforated pipes in the mufflers with straight pipe. That's all there is to it. Same as N54.

[Soden82]

You're just cutting open the muffler, removing the packing and welding a stainless steel pipe into the muffler to connect the muffler to the rest of the exhaust. Then putting the packing back in and welding the muffler back together

[E92n55slo]

Mod bargains makes a YouTube video describing the process

[DYOOS]

I'm also reading about an X-pipe or H-pipe that can be replaced with a straight pipe. Would getting that done make the car much louder?

[bcaz808]

I'm PS2, catless and pe mod. The car is pretty loud imo. If I were to do it over I would've only modded the driver side muffler, that's where the resonator is. The passenger side muffler is just a perforated pipe.

[DYOOS]

Originally Posted by bcaz808

I'm PS2, catless and pe mod. The car is pretty loud imo. If I were to do it over I would've only modded the driver side muffler, that's where the resonator is. The passenger side muffler is just a perforated pipe.

Yeah, not trying to go loud right now. I'd like to also stay smog-friendly. Even though PS2 and catless (among other things) is what I'll ultimately do

Has anyone also replaced their stock mufflers with an aftermarket one by getting them welded on?

[maddmatth]

Originally Posted by bcaz808

I'm PS2, catless and pe mod. The car is pretty loud imo. If I were to do it over I would've only modded the driver side muffler, that's where the resonator is. The passenger side muffler is just a perforated pipe.

To compensate for the extra volume and metallic sound you get from going catless, you can add 2x vibrant resonators before the mufflers.
Google PE mod and vibrant resonators if you'd like to research further, it'll lead you to some other threads around here.

[renizer]

Originally Posted by bcaz808

I'm PS2, catless and pe mod. The car is pretty loud imo. If I were to do it over I would've only modded the driver side muffler, that's where the resonator is. The passenger side muffler is just a perforated pipe.

what do you mean by "resonator on driver side only"? i thought both sides act as resonators in stock form, with the perforated pipe and glasswool or w/e packing inside? only diff is that driver side has the flap

[bcaz808]

Originally Posted by renizer

what do you mean by "resonator on driver side only"? i thought both sides act as resonators in stock form, with the perforated pipe and glasswool or w/e packing inside? only diff is that driver side has the flap

Drivers side has an actual resonator inside the muffler, passenger is just perforated pipe. Do a google search and you can find images of what I am talking about.

[northbranchroad]

Originally Posted by maddmatth

To compensate for the extra volume and metallic sound you get from going catless, you can add 2x vibrant resonators before the mufflers.
Google PE mod and vibrant resonators if you'd like to research further, it'll lead you to some other threads around here.

What is this metallic sound? I definitely have it.

[renizer]

Originally Posted by bcaz808

Drivers side has an actual resonator inside the muffler, passenger is just perforated pipe. Do a google search and you can find images of what I am talking about.

Ok I was looking around for a pic and found one with the internals still intact (before cutting them out) and saw the resonator in the driver side part, indeed! Thanks for the pointer.


Btw, being an xi, mine has I think secondary cats in the front and then only the X-Pipe after that before the rear double-muffler but that muffler is the same for all models, right?

[bcaz808]

Originally Posted by renizer

Ok I was looking around for a pic and found one with the internals still intact (before cutting them out) and saw the resonator in the driver side part, indeed! Thanks for the pointer.


Btw, being an xi, mine has I think secondary cats in the front and then only the X-Pipe after that before the rear double-muffler but that muffler is the same for all models, right?

AFAIK.

[DYOOS]

Originally Posted by renizer

Ok I was looking around for a pic and found one with the internals still intact (before cutting them out) and saw the resonator in the driver side part, indeed! Thanks for the pointer.

So looks like the driver side has a resonator and a perforated pipe. Would this be the same for a RWD 335i? Can you replace that perforated pipe with a straight pipe?

[renizer]

i think the dual muffler are like this for all 335i's, xi or not.
and for the perforated (inner) pipes, as far as i know these should not be replaced, only the outer ones!

edit:
here's a primer for the N54 which i found helpful but always welcome to exchange experiences for the specific application like for the N55 in your thread here
https://www.e90post.com/forums/showthread.php?t=739970

Originally Posted by elim11

Process
Those with N54's can reproduce the sound I have by:
1. Replacing [i-pipe] resonator with X pipe (if you have an e90. e92's don't have a resonator). A 2.5” stainless Xpipe will work. Check question 2 in the FAQ for a link if you’re lazy. 
2. [dual muffler mods from here on] Replacing both outside perforated pipes with solid pipes. The driver side muffler will have an internal muffler resonator. Chop that crap off and replace with solid pipe. See the first image for a pic of the internal muffler resonator
3. Don't remove any packing. As WhiteFury mentioned, no sound should be coming out of the areas with solid piping anyway, but it will likely absorb "ambient" (unwanted) noise from the muffler.
4. DownPipes

...from the FAQ:
5. Q. Is the Xpipe necessary for the e92?
A. The e92 already has an Xpipe, whereas the e90 has a resonator. Therefore, e92 owners don’t need to install an Xpipe.

so as for differances, as far as i know, LCIs/N55 don't have that (E90) resonator in front of the back end muffler.. at least my E91 doesn't have it either. not sure about the resonator in place of the x-pipe? as said above mine only has the x-pipe and the dual muffler in the back, and secondary cats because it's an xi according to this and other threads.
http://www.e90post.com/forums/showthread.php?t=1310008

Originally Posted by Rahim e92

All N54 have secondary cats. N55 do not unless it's xDrive

even better infos here on N54/N55 differences:http://www.e90post.com/forums/showthread.php?p=14676643

Originally Posted by DYOOS

I'm also reading about an X-pipe or H-pipe that can be replaced with a straight pipe. Would getting that done make the car much louder?

from my research on here so far it seems the x-pipe will make the sound more "balanced", refined, or whatever you wanna call it.. think it's better to retain/add it.

bcaz808, what's your exact setup other than catless DPs and the PE mod?
i think i understand now what you're saying about the driver side integrated resonator..

i'm guessing if you want it loud on tap, you could only change the driver side resonator for a solid outer tube, because this one only works with the flap (so, either automatic (stock) flap control or have an on/off control). if you want to have a louder exhaust in general, you could also change the passenger side outer tube since that one is always open?

[Ludilo]

The rear mufflers of an 2009/2010 335 XI would be the same/fit on my 2011 335i X Drive correct? Friend has his from the N54 laying around- wanna buy it so I can do the PE mod.

[Kevin39]

As long as they are both coupes or both sedans they should be interchangeable

[PDR]

I plan on doing this mod this weekend. What size clamps do I need to purchase? I'd like to try and source locally if possible, so something from a big box store would be great.

If necessary I will replace with OEM clamp later down the road, but the weather will be optimal and I have the weekend off.

[renizer]

http://bmwfans.info/parts-catalog/E9.../rear_muffler/
maybe this helps

[bcaz808]

Originally Posted by PDR

I plan on doing this mod this weekend. What size clamps do I need to purchase? I'd like to try and source locally if possible, so something from a big box store would be great.

If necessary I will replace with OEM clamp later down the road, but the weather will be optimal and I have the weekend off.

2.25" iirc. I dropped the exhaust from the downpipe back instead of cutting the mufflers off.

[katatonia]

Originally Posted by DYOOS

So looks like the driver side has a resonator and a perforated pipe. Would this be the same for a RWD 335i? Can you replace that perforated pipe with a straight pipe?

I just did this. Replace perforated with straight, stuff the soft stuff back in and weld back together

[Mikaeldarer]

This is how I did mine... I have also seen people wrap the perforated pipes with cut up aluminum cans and worm clamps. https://www.e90post.com/forums/showthread.php?t=1364483