ZPOST
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   ZPOST > BMW Z4 Technical Talk > Engine, Exhaust, Drivetrain Modifications
  TireRack

SUPPORT ZPOST BY DOING YOUR TIRERACK SHOPPING FROM THIS BANNER, THANKS!
Post Reply
 
Thread Tools Search this Thread
      03-06-2016, 11:38 PM   #1
doane2u
First Lieutenant
United_States
91
Rep
341
Posts

Drives: 2012 135i M Sport E88
Join Date: Jan 2016
Location: Carmel, CA

iTrader: (0)

Question Economical exhaust sound improvement?

I have a stock 2007 3.0i that I got recently. I would like to enhance the exhaust sound a bit with out making it raspy or obnoxious to others or too loud while cruising. I just would like to lower the octave and increase the level a bit. The stock muffler just doesn't seem very exciting for this beautiful car!
Performance increases aren't that important, I'm only wanting to replace the muffler which isn't going to change too much except for the sound, I'm not interested in replacing the whole exhaust system and it will have to pass the California emissions checks.
Any ideas on what I might be able to get at a local muffler shop? I looked under the rear and it looks like the muffler is attached to the pipe to the cat so would have to be cut in order to replace it? What is normally done?

Thanks
Appreciate 0
      03-08-2016, 09:09 AM   #2
doane2u
First Lieutenant
United_States
91
Rep
341
Posts

Drives: 2012 135i M Sport E88
Join Date: Jan 2016
Location: Carmel, CA

iTrader: (0)

No one has done this?
Appreciate 0
      03-08-2016, 10:30 AM   #3
pokeybritches
Colonel
pokeybritches's Avatar
United_States
479
Rep
2,782
Posts

Drives: ESS/G-Power Z4M, VF Z4, 996tt
Join Date: Sep 2009
Location: Los Angeles

iTrader: (12)

Garage List
2006 BMW Z4M  [10.00]
2006 BMW Z4M  [8.50]
2003 BMW Z4 3.0i  [9.00]
If your car is anything like the 2003-2005 M54 Z4 and 2006+ Z4M, the primary cats are in the headers. Any secondary cats are unmonitored. It's illegal to have the secondary cats removed, and many shops may refuse to mess with them due to potential fines. But, no one will really know if they've been removed, you will more than likely still pass a visual and sniffer as long as the primary cats are in place, and the car won't throw any codes if all the sensors are monitoring the primary cats in the headers (you will need to visually confirm).

Anything aft of the cats is fair game, as long as you don't break any noise laws.

The exhaust on the early Z4's is one piece from the headers back. Most mufflers are cut and clamp. You will need to put the car on the rack to confirm.

If you have both sets of cats in place, you can put just about any kind of muffler on the car without it sounding terrible. Once you start removing cats or resonators, the car will need a tuned muffler from a name brand company.

I personally wouldn't put a universal muffler on my car.
__________________


VF Engineering Z4 3.0i, ESS Z4M, G-Power Z4M, 996 Turbo
Appreciate 0
      03-08-2016, 10:57 AM   #4
pokeybritches
Colonel
pokeybritches's Avatar
United_States
479
Rep
2,782
Posts

Drives: ESS/G-Power Z4M, VF Z4, 996tt
Join Date: Sep 2009
Location: Los Angeles

iTrader: (12)

Garage List
2006 BMW Z4M  [10.00]
2006 BMW Z4M  [8.50]
2003 BMW Z4 3.0i  [9.00]
If your car has secondary cats, I would relocate the secondary O2 sensors aft of the secondary cats (possibly with defoulers) and go with catless headers. That way you get the sound increase and power to go along with it, while retaining an OEM-looking exhaust. If you want more sound, then get an aftermarket muffler.

There is risk involved, since the secondary cats may not clean up the exhaust fumes enough to pass the sniffer or avoid a CEL. It depends on what you're after and how much risk you're willing to take on. Deleting the primary cats will likely result in a 10-15 whp gain.
__________________


VF Engineering Z4 3.0i, ESS Z4M, G-Power Z4M, 996 Turbo
Appreciate 0
      03-09-2016, 11:51 PM   #5
doane2u
First Lieutenant
United_States
91
Rep
341
Posts

Drives: 2012 135i M Sport E88
Join Date: Jan 2016
Location: Carmel, CA

iTrader: (0)

Thanks, Pokey
Appreciate 0
      09-17-2016, 12:16 PM   #6
3002 tii
Lieutenant General
3002 tii's Avatar
2272
Rep
12,559
Posts

Drives: Z4 M, X5, GX460
Join Date: Apr 2008
Location: CT

iTrader: (99)

Garage List
I would just delete the secondaries and swap mufflers for something like a Borla or Magnaflow and finish off with whichever tips you like. Should run you maybe $350-500.

You will pass emissions without secondaries. Keep them around in case you want to reinstall.
__________________
Follow for latest mods
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 09:00 AM.




zpost
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST