Biting the bullet... Magnaflow mufflers - Page 5 - The Unofficial BMW M5 Messageboard (m5board.com)

Beasty5 · 17th October 2007, 09:38

+1 on the sound. You know for sure that was a v8 blasting by. Nice!

Vic

Carbon01 · 23rd December 2007, 17:46

Good morning,
For those of you that have had your exhaust in place for a few months...

I just had a set of 14815s put on my car as well (6 days and about 300 miles ago) and have noticed the following and wondered it it was what you experienced. (I had them remove the stock 2.25" inlets and weld 2.5" pipe directly to the muffler, system stock otherwise - no X-pipe).

1.) the fuel economy has dropped about 1/2 mpg (could be driving style, but I've tried to drive exactly as I used to since I noticed it. I've gone from 17.2 in town to 16.7)
2.) There is the 1500 rpm drone others have noted
3.) The rpms don't seem to rise as fast (if you stab the throttle, it doesn't rev as quickly)
4.) There is a little throaty in-muffler "gasp" or burble when you let off the throttle for just a second. It is noticeable between shifts or if you accellerate and let off. My wife described it as "your exhaust pops now", but it is def. not a pop... just a muffled burble.

These observations seem like by-products of being more constricted than before, but maybe its just me. I've read every exhaust thread on this board relative to Kelleners, Dinan, and Magna so I'm familiar with the flow discussions. But I figured I'd ask if these findings mirrored your experiences as well.

The sound couldn't be better, and they got them high and tight - they look great. Just fretting the details as I don't want to take any steps back performance wise.

Thanks in advance!

xr4tic · 23rd December 2007, 20:08

I recently had a pair of 14815s installed, they have ~600 miles on them.

They did the same thing, cut the inlet off, and welded on 2.5" pipe.

1) I haven't noticed a drop in MPG, with the colder weather around here, it's hard to tell.

2) There is 1500 RPM drone, but I noticed the stock mufflers did the same thing, just that it wasn't as noticeable. No big deal, just means I cruise in 5th gear at 45mph instead of 6th (or speed up to 50 mph)

3) I haven't noticed this. Maybe it's subjective, based on only hearing the engine sounds, compared to hearing the engine and exhaust sounds.

4) This is normal of a freer flowing exhaust. Listen to any V8 "muscle car" (or race car for that matter) and it will have the same sound on decel. Personally, I like it.

I love the sound, I still think it's a little too quiet, but I'll give it some time to break in.

It's definately not more restrictive than stock, you can see straight through the muffler. I'm tempted to cut open one of the stock mufflers, just to see what's inside.

How are your MAFs? O2 sensors? how many miles on your car? I just recently replaced my MAFs and O2 sensors, so maybe you have other problems and the mufflers are making the problems worse?

azaytsev · 23rd December 2007, 20:18

How long does it take for Magnaflows to break in? How much louder should they get?

Carbon01 · 23rd December 2007, 20:31

The car is tight and solid, just turned 40k miles and has no issues of which I am aware... it runs very strong and doesn't burn a drop of oil. All tune up items are up to date, and no codes of any kind.

Much of this is subjective I'm sure as I didn't foften ree rev the engine before, nor did I pay as much attention to every detail. Just seeing if others experienced any of this as well.

I will say the sound is spot on with what I wanted... just perfect. Not too loud and deeper with a bit more of the engine's attitude shining through. Sounds no different from the inside at freeway speeds.

As for item #4 - would this would be the same thing I would hear from a Dinan or other aftermarket system as well? I attributed it to these mufflers not being specifically tuned to this engine's exhaust flow characteristics. Again - I don't mind it, just wondering as I've not heard another M5 with aftermarket exhaust.

Cantresjr · 24th December 2007, 02:33

TMRM5- do you have video or sound clips on your system, I would like to hear it.

Thanks

Beasty5 · 24th December 2007, 13:06

1.) the fuel economy has dropped about 1/2 mpg (could be driving style, but I've tried to drive exactly as I used to since I noticed it. I've gone from 17.2 in town to 16.7.
I noticed my mpg dropped by .5 as well. I use to get 19.1 mixed driving, but now get 18.6 with same driving style(no biggie)
2.) There is the 1500 rpm drone others have noted
Love the mild drone bellow 2000rpm. Reminds me I have aftermarket exuast.
3.) The rpms don't seem to rise as fast (if you stab the throttle, it doesn't rev as quickly)
Quite the contrary in my case. Beasty revs faster.
4.) There is a little throaty in-muffler "gasp" or burble when you let off the throttle for just a second. It is noticeable between shifts or if you accellerate and let off. My wife described it as "your exhaust pops now", but it is def. not a pop... just a muffled burble.
Normal. The Mag is free-flow/less restriction than stock hence the burble. Most aftermarket exausts do this. I listened to quite a few.

Give the Mags time to break-in. It takes close to 2000 or more miles to develope its full tone. I now have ~2000 miles on my 14816s and it sounds throatier and the drone has subsided significantly but still noticeable. I love it. You will too over time/milage.

Carbon01 · 17th February 2008, 18:55

I thought I'd share some follow up information regarding the Magnaflow system.

I put about 2200 miles on the Magnaflows before replacing with a Dinan system. I had had the stock inlets removed and had 2.75" pipes welded directly to the mufflers. They were not mandrel bent on their way to the joint with the car's exhaust pipes at the axle.

These were my initial observations after install:

1.) the fuel economy has dropped about 1/2 mpg (could be driving style, but I've tried to drive exactly as I used to since I noticed it. I've gone from 17.2 in town to 16.7)

Follow up: After a few hundred miles this raised slightly, but never back to what it did before.

2.) There is the 1500 rpm drone others have noted

Follow up: This never went away but you notice it less as you get used to it.

3.) The rpms don't seem to rise as fast (if you stab the throttle, it doesn't rev as quickly)

Follow up: This was hard to qualify as to whether this was actually the case or a result of the enhanced sound and not hearing the raw engine noise as much with the exhaust note.

4.) There is a little throaty in-muffler "gasp" or burble when you let off the throttle for just a second. It is noticeable between shifts or if you accellerate and let off.

Follow up: This became a little more pronounced as the mufflers broke in.

So, I ended up replacing the Magnaflows with Dinans. Here are my initial 300 mile observations:

The Magnaflows sound much better. This is subjective of course, but they are much deeper and authoritative. The Dinans are a little more "trebly" and just lack the deepness of tone. They don't sound bad, and had I not heard the Magnaflows I wouldn't know any better, but it is what it is. Advantage: Magna
The Dinans have the same resonance at 1500 rpms, and the same "in muffler burble" the magnaflows did, but to a slightly less degree.
The primary difference however lies in how the system "works" with the engine. The engine revs instantly, and the throttle response is better everywhere, particularly in the upper gears (say... accelerating in 6th from 70mph). And fuel economy jumped noticeably right away. I drove it exactly like I do every day and it maintains mid to high 18s now. I attribute these two observations to the much larger head pipes on the Dinan system and the fact that they are mandrel bent with no constraint through the bends. I haven't measured them, but would guess they are 3" or slightly larger all the way from the car's pipes near the axle through the muffler inlets. Side by side, these pipes are much larger than the 2.75" I had done on the Magnas and are clearly larger than the factory exhaust they attach to. I remember thinking I should have requested 3" on the original install, but it would be pointless when the Magnaflow inlet was only 2.75". The engine pulls smoother all the way to redline...This can't be understated... it is very noticeable especially in back to back driving. Advantage: Dinan (at least where the smaller 2.75" inlet Magna is compared).
The Dinans are definately quieter than the Magnas, undoubtedly due the greater interior volume of the muffler and some baffling. Probably by 10-15 percent at a minimum. This is a plus for me in terms of interior resonance, tho I miss the deeper tone of the Magnas.

Performance wise the Dinans have the edge, perhaps not the 1200 - 1500 dollars worth that represents the delta in cost - but thats an individual decision. It was worth the delta for me as something just wasn't "right" and that is what led me to buy the Dinans in the first place. Soundwise - the Magnaflows are much better to my ear. If they come up with something with a larger inlet and set up for the M5 I'd be tempted to jump back. For now I'll keep the Dinans because I love the way the car runs with them. I also like the staggered outlets on the Dinan, ala the stock tailpipes. I look forward to hearing and seeing the variety of cans that will be present at MFest.

Sorry for the length of this post. Hope it was helpful. That's a stock and two aftermarket exhausts in three months. We'll see what next quarter brings... heh heh.

M55555 · 17th February 2008, 19:23

Quote:

Originally Posted by Carbon01

They were not mandrel bent on their way to the joint with the car's exhaust pipes at the axle.

The primary difference however lies in how the system "works" with the engine. The engine revs instantly, and the throttle response is better everywhere, particularly in the upper gears (say... accelerating in 6th from 70mph). I attribute these two observations to the much larger head pipes on the Dinan system and the fact that they are mandrel bent with no constraint through the bends..

I think you nailed it there, Dinan obviously has the most efficient exhaust flow in this setup. I wonder if you'd notice any difference between the two in terms of throttle response if the magnaflows had been installed with optimal piping bends.

iconoclast · 17th February 2008, 19:25

nice comparison... thanks for the info/insight.