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      10-12-2014, 01:47 PM   #1
parky1215
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Review: Stock F80 M3 / M4 exhaust in various modified configurations (/w videos)

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Setup 1: Stock exhaust with stock midpipe (valve flap disabled)
Stock M3 exhaust is fairly loud exhaust even without any modification.
However, it was not exactly the tone that I was looking for.

Some problems with stock exhausts are…
Not so impressive cold start sound
Raspy and too farty at high RPM
Exhaust is pretty muted at partial throttle due to valve flap
Does not really produce much pop and crackle noise
It is really ugly to look at

Stock exhaust is made of various components as shown in the picture below.



To improve cold start and partial throttle issue, I decided to try golf tee mod on my M3.
Technically speaking, golf tee is no longer valid term for new M3.
New M3’s valve is now electronically controlled instead of vacuum line.

Disabling exhaust valve flap definitely improved cold start sound.
You can also feel exhaust singing on every RPM even during partial throttle application.
Improvement is due to the exhaust valve being kept open to minimize exhaust flow going to central part of rear muffler where the sound is heavily dampened.

While I enjoyed sound improvement, it brought up one big issue.
DRONE!!!

Because most exhaust gas is now exiting directly via straight pipe and non-muffled area, it caused some drone to appear during regular cruising.
Drone happened between 1.8k to 2.2k RPM range on my DCT M3.
I reconnected valve flap controller back after few days because drone was getting annoying.


Setup 2: Stock exhaust with secondary catalytic converters removed from midpipe (valve flap enabled)
With failed attempt at golf tee mod, I decided to try something different to improve stock exhaust’s sound.
This time, I decided to perform secondary cat delete mod.

New M3 comes with secondary cats in the midpipe… and they look like pretty restrictive ceramic cats.
There are no sensors around these secondary cats, so removing them will not throw any emission related CEL.





Driving car with secondary cats delete mod increased sound volume especially on mid RPM range.
Exhaust flapper is also doing its job, so there was no drone at all.
Unfortunately, ugly farting noise at high RPM also got louder and cold start still sounded bad.


Setup 3: Stock exhaust with secondary catalytic converters removed from midpipe (valve flap disabled)
Just to experiment, I decided to disable exhaust valve flap from previous exhaust configuration.
Car is actually really loud with this setup, but drone is even worse than my first setup.
I didn’t really like this setup.


Setup 4 (Current Setup): Stock exhaust with secondary catalytic converters replaced with MagnaFlow race mufflers (valve flap disabled)
I didn’t intend to pair up Magnaflow race muffler with stock exhaust.
I originally got it to reduce drone from my aftermarket exhaust (Meisterschaft GT Racing), but it did not work that well. I ended up selling Meisterschaft.

MagnaFlow that I got is one of their race series mufflers (MagnaFlow part #14156).
They are more expensive than normal resonators, but I did not want to put cheap glasspack muffler in my M.
These are properly tuned straight-through muffler built with high quality sound-dampening material.







When EAS was putting my stock exhaust back, I asked them to leave exhaust valve flap disabled.

So how does my new exhaust system sound?
One word: Excellent!

These little mufflers made some significant difference in how stock exhaust sounds.
First of all, my exhaust tone got deeper.
Difference is noticeable pretty much at every RPM.
Exhaust is slightly louder than stock setup with secondary cats /w valve flap disabled.
It also reduced that ugly farting and raspy noise emitted at high RPM shift.

Cold start sounds so much better.
I can now proudly turn on the car parked inside underground parking lot.

Best of all, most drone is eliminated even with golf tee mod.
With my exhaust setup 1 (Stock exhaust with stock midpipe, valve flap disabled), I would get drone between 1.8 to 2.2k rpm on upper gears.
With MagnaFlow midpipe setup, drone is completely eliminated on most upper gears (4, 5, and 6).
I still hear minor drone at 7th gear between 1.8k to 2.1k rpm, but it is very minimum.
Since it only drones little bit in 7th gear, I can easily get out of it by downshifting to 6th whenever moderate acceleration is needed.

Overall, I am pretty happy with this current setup as it solved many issues that I had with stock exhaust system.
Price to get this done is fairly cheap too.
Each MagnaFlow muffler costs around $140. You need 2 of these + cost to get these welded ($150-200).
For about $450, you can have really nice sounding and fairly loud exhaust system that can be used for daily duty.
I still wish to hear more pop n crackle noise, but that one may require completely different exhaust setup.

Here are some videos that I took with MagnaFlow muffler midpipe setup.

Driving around the town (several 1-2 gear pull with varying throttle)


My car on EAS dyno


Revving after dyno

Last edited by parky1215; 11-10-2014 at 11:34 AM.
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      10-12-2014, 03:31 PM   #2
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I like this. If I choose to mod this exhaust this is what I will do. Much better than the aftermarket options so far imo

The midpipe mod was the best thing for sound on the 1m too.

Nice work!
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      10-12-2014, 03:53 PM   #3
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Fantasic post. Great to finally hear it! Most likely going this route as well!
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      10-12-2014, 03:54 PM   #4
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Kool setup. Didn't hear much of a difference IMO.
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      10-12-2014, 04:20 PM   #5
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wow that sounds awesome! A lot better then I expected.
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      10-12-2014, 08:50 PM   #6
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great post
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      10-12-2014, 11:39 PM   #7
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Great write-up. Thanks.
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      10-13-2014, 12:26 AM   #8
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Thanks VERY much for posting up all of these details. I (and I'm sure MANY others) sincerely appreciate it, as clearly the exhaust sound is one of the few minuses on this car that people tend to agree on. I'm not familiar enough with the stock exhaust to know what that sounds like in comparison (I currently own an E93 M3 with an OEM Exhaust Mod) but I wanted to share my appreciation for you posting these details, as it's these types of posts that lead my to consider and ultimately perform the OEM Exhaust Mod on my current E93 M3 and it was the best mod I had ever done to a car I have owned.

So thanks again for sharing - it's much appreciated!
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      10-13-2014, 12:28 AM   #9
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Would love to hear this. Any chance you come out to ventura county ever? Would you be interested in coming out to Camarillo Cars and Coffee?
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      10-13-2014, 09:15 AM   #10
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Thanks for the write up!

1) How do you disable the exhaust valves?

2) Part number for the Magnaflows?
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      10-13-2014, 10:18 AM   #11
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"MagnaFlow that I got is one of their race series mufflers (MagnaFlow part #14156)".. per OP.
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      10-13-2014, 06:39 PM   #12
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Thanks everyone for positive comments.
Hopefully, my experiments will save some $$$ for many M drivers.

Quote:
Originally Posted by Definitive View Post
Would love to hear this. Any chance you come out to ventura county ever? Would you be interested in coming out to Camarillo Cars and Coffee?
I don't visit that area that much since it's 2 hours from my home.
And doesn't C&C have no 4-door policy or something like that?

Quote:
Originally Posted by MaynardZed View Post
Thanks for the write up!

1) How do you disable the exhaust valves?

2) Part number for the Magnaflows?
1. Just drive around the town in sport mode. When you shut off the engine, valve should still be open. After exhaust cools down, get under the car and disconnect cables that connect to valve controller.
2. http://www.magnaflow.com/02product/d...rtnumber=14156
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      10-13-2014, 08:42 PM   #13
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These aero turbine resonators are really popular for the e46 m3. They worked pretty well.

I may try these in place of the secondary cats. Not sure how they would compare to magnaflow

http://www.aeroexhaust.com/resonators/ar25.html
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      10-13-2014, 11:02 PM   #14
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Definitely worth a try!!!
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      10-13-2014, 11:08 PM   #15
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I've actually been thinking of a full custom exhaust using these two small ones and two large ones in the rear. I would definitely be a guinea pig as I've never seen a "custom" exhaust on an M before. LOL.
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      10-14-2014, 11:32 AM   #16
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Quote:
Originally Posted by KennyPowers View Post
These aero turbine resonators are really popular for the e46 m3. They worked pretty well.

I may try these in place of the secondary cats. Not sure how they would compare to magnaflow

http://www.aeroexhaust.com/resonators/ar25.html
Isn't there a difference between a race muffler and a resonator?
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      10-14-2014, 11:47 AM   #17
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Quote:
Originally Posted by farbmw View Post
Isn't there a difference between a race muffler and a resonator?
im not really sure, Im pretty sure they work the same? But im no expert

typically cats are replaced by resonators or straight pipe.

EDIT : thanks for raising this question, I learned something See link below, they are in fact different. Seems a muffler is a more ideal solution, but impossible to know for sure without trying it

http://www.fordmuscleforums.com/all-...resonator.html
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      10-17-2014, 05:49 PM   #18
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any difference in performance?
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      10-17-2014, 06:27 PM   #19
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Quote:
Originally Posted by farbmw View Post
Isn't there a difference between a race muffler and a resonator?
Quote:
Originally Posted by KennyPowers View Post
im not really sure, Im pretty sure they work the same? But im no expert

typically cats are replaced by resonators or straight pipe.

EDIT : thanks for raising this question, I learned something See link below, they are in fact different. Seems a muffler is a more ideal solution, but impossible to know for sure without trying it

http://www.fordmuscleforums.com/all-...resonator.html
I believe Magnaflow race muffler is pretty similar to straight resonator.
Only difference would be type of material used to dampen the sound.

Quote:
Originally Posted by karbonphiber View Post
any difference in performance?
You would get few HP by removing secondary cats.
But it's not something that is really noticeable.
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      10-18-2014, 11:30 PM   #20
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Great post! I was considering leaving the stock exhaust and just getting c@tless downpipes, but after reading your post, this might not be a bad option also.
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      10-21-2014, 09:04 AM   #21
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I'm surprised for fun you didn't do one with just straight muffler delete. I really want to know if it's just horrible sounding or similar to stock but louder.
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      10-21-2014, 11:15 AM   #22
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It sounds great...i think i'll try this. Hope it is the same for a m4
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