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      09-03-2012, 09:18 AM   #1
elim11
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Drives: e90m3
Join Date: Apr 2008
Location: irvine/sf

Posts: 619
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Modify OEM exhaust to sound like PE exhaust

I got some inspiration from the M3 guys who are modifying the stock exhausts to become more aggressive sounding. http://www.m3post.com/forums/showthread.php?t=720030

Anyone know what the differences are between the stock 335i exhaust and the BMW performance exhaust? Both seem like the use the same muffler housing dimensionally. I'm guessing the internal baffling and insulation is different, but by how much.

It would be awesome if we could just modify our stock exhausts for a couple bones and achieve a PE-type tone and sound. I'm sure it would be VERY popular. It might be wishful thinking, but I figure I throw it out there.

(Not interested in the catless DP + stock, or the golf tee mod sounds.)

EDIT(thanks to Secretsquirrel):

Background
Elim11 started this thread to inquire about emulating the mod that many M3 owners use to modify their stock exhausts in order to achieve a PE-type sound. After the contributions of many members, we’ve finally got a similar sound with savings of about $1000!

This write-up was created to keep people from having to sift through the mountain of information contained within this thread. Elim11 has moved on to another vehicle and doesn’t frequent this this forum often. So, please feel free to direct your questions towards SecretSquirrel or others who’ve shown willingness to answer questions. But please, read this overview thoroughly before doing so. I’d like to not duplicate the effort if it’s already here.

Special credit: apjr09, Ripley, Glowin, WhiteFury, SecretSquirrel and many others who’ve contributed to this. I apologize if I missed someone. This was a group effort and we appreciate everyone who devoted their time for the community.

Process
Those with N54's can reproduce the sound I have by:
1. Replacing 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. 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

Pictures for illustrating the process to your exhaust shop.
What the exhaust looks like when the mufflers are cut open.
Credit, Unsure. Please let me know who you are so I can credit you appropriately


What the exhaust looks like once the perforated section and internal muffler resonator is cut and ready to be replaced with solid 2.5” pipe. *Please note that the internal muffler resonator is different than the resonator on the e90 that sits about 18” before the mufflers.
Credit. Javy, post 852 http://www.e90post.com/forums/showpo...&postcount=852


What the exhaust will look like once it has been modified and is ready to have the packing replaced and welded shut.
Credit, Unsure. Please let me know who you are so I can credit you appropriately


Videos
1. WOT video

Ripley, http://www.e90post.com/forums/showth...0#post15086160

2. Start up, rev and slow driving

SecretSquirrel, Post 968 http://www.e90post.com/forums/showpo...&postcount=968


FAQs
1. Q. How much labor does the mod cost?
A. You can count on the mod costing anywhere from $250 to $400. A quick estimate of labor time: muffler mod (2 hours), Xpipe install (45min), new tip installation (30 minutes).
Note: The Xpipe requires 8-12 inches of 2.5”piping in order to gradually flow into the exhaust. Just suggest that they use scrap metal for this as any exhaust shop will have tons of 2.5” piping laying around.

2. Q. How much for parts?
A. The Xpipe should cost you around $40. Make sure it is 2.5” and stainless.
Note: Don’t show up to an exhaust shop without your parts. They will attempt to sell you a Magnaflow xpipe for 100-125. Get this one for about 40 shipped. http://cgi.ebay.com/ws/eBayISAPI.dll...m=151258323391
Tips should cost you $70-150. Check out Cyba or Dimisa, but any 2.5” inlet tip will work. I used the 2.5” inlet, 4” tip at http://www.autoanything.com/exhausts...ed-exhaust-tip. Just make sure the shop welds them with the name pointed down.

3. Q. Is it loud?
A. No, the mod is not loud (with or without DPs). The normal driving volume is about as loud as the exhaust on an Infiniti FX. It also has a very similar “rhythm”. The great thing about the exhaust is its ability to be louder when wanted, but quiet enough that you can conduct a teleconference while driving on the highway. But you can also make it loud enough so that everyone every one notices you by giving it light throttle presses.

4. Q. Any drone?
A. No, there is absolutely no drone with or without catless DPs.

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.

6. Q. Is it necessary to replace all the packing?
A. I don’t know if it’s necessary, but IMO it’s a good idea to do as it should absorb some of the sound that circulates within the exhaust. Some have experimented with removing different amounts of packing, or removing packing from one side of the exhaust with varying results. Removing packing seems to have a limited upside at this point.
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Last edited by elim11; 04-14-2014 at 12:22 PM.
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