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2010 2011 BMW 5 Series Forum F10 F10 Technical Topics Engine, Transmission, Exhaust, Drivetrain, ECU Software Modifications M5 exhaust on 550 in Houston area?
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      01-22-2014, 07:00 PM   #23
Mbbrewer
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So how does the xpipe work? Do the tubes open up to each other where they connect? What's the point of this?
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      01-22-2014, 08:51 PM   #24
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For exhaust "tone"

Quote:
Originally Posted by Mbbrewer View Post
So how does the xpipe work? Do the tubes open up to each other where they connect? What's the point of this?
My understanding is an X pipe for a turbo V8 help synchronize the sound waves from each exhaust bank a bit. The pipes are siamesed with an oval shaped cut where they connect. The point, well, not so much for power (strong debate that X or H pipes are of no benefit on a turbo V8) but instead for exhaust tone. Of course that is very subjective as some folk like deep and loud (they’ll be the ones using 3” straight pipes) while others like higher pitched, controlled sound. Listen to scott135i before and after sound clip. I hear a subtle, but noticeable change with the x pipe. I plan on having some mandrel formed pipes up to the M5 muffler. The big bonus for me then is the elimination of the bent and kinked mid pipes with the restrictive canister. I really like how scott’s 550i M5 mufflers with x pipe sounds so, at least for me, that’s my plan.

Last edited by HDEddie1; 01-22-2014 at 08:58 PM..
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      01-25-2014, 08:06 AM   #25
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Quote:
Originally Posted by HDEddie1
Quote:
Originally Posted by Mbbrewer View Post
So how does the xpipe work? Do the tubes open up to each other where they connect? What's the point of this?
My understanding is an X pipe for a turbo V8 help synchronize the sound waves from each exhaust bank a bit. The pipes are siamesed with an oval shaped cut where they connect. The point, well, not so much for power (strong debate that X or H pipes are of no benefit on a turbo V8) but instead for exhaust tone. Of course that is very subjective as some folk like deep and loud (they’ll be the ones using 3” straight pipes) while others like higher pitched, controlled sound. Listen to scott135i before and after sound clip. I hear a subtle, but noticeable change with the x pipe. I plan on having some mandrel formed pipes up to the M5 muffler. The big bonus for me then is the elimination of the bent and kinked mid pipes with the restrictive canister. I really like how scott’s 550i M5 mufflers with x pipe sounds so, at least for me, that’s my plan.
The difference is subtle in the video but different in real life. It's deeper, a bit louder, and burbles/pops at WOT up shifts with the x-pipe.

I am convinced the x-pipe might add some power not because of the actual crossover itself but because I removed the center muffler so the power gains (if they're real) would be there with straight pipes as well, just not as good as balanced sound. The center muffler acts as an x-pipe, as it collects from both pipes.

The x-pipe is a no brainer if you're doing m5 mufflers unless cost is a factor for you. The m5 mufflers are nice, add sound and look cool, but are just a little quiet, especially inside the super well isolated f10 cabin.
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      01-25-2014, 08:13 AM   #26
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Great description.
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      01-25-2014, 06:19 PM   #27
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Scott as a %, how much of an increase in sound does the xpipe make?
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      01-25-2014, 11:40 PM   #28
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Quote:
Originally Posted by xiljustin View Post
Scott as a %, how much of an increase in sound does the xpipe make?
I have no decibel gauge, but if I had to guess using my untrained ear.... I would say the x-pipe made the exhaust 10% louder at idle or while driving and maintaining speed/RPM. While accelerating 50% throttle, it is probably 20% louder, and while accelerating 100% or Wide Open Throttle (WOT), probably 35-40% louder.

Note, I am using the flaps in the oem m5 mufflers (the same ones that are on the oem 550i exhaust), which is why the % increase in volume changes as a function of RPM since the flap opens at a certain RPM (I believe around 3/3.5k rpm).

Here is a good measure - my girl...

1. At cold startup, she noticed it was deeper and louder, at idle once the engine is warm, she couldn't tell.
2. While driving and maintaining speed/rpm she thought it was a 'tad' louder but not really noticeable,
3. At 50% throttle or WOT, she said it was "quite a bit louder", "sounded good" and "was not annoying". She even said, "it must sound even better if you're outside and behind the car".

Ha....
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      01-27-2014, 08:41 PM   #29
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Hey Scott,
I noticed the flap valve is on the outboard side of our car...did you just pick up some vacuum tube (3/8" I presume) at the part store and connect with a double sided nipple to extend the stock tube?
Also, I presume drone at part throttle is non issue before the X pipe and after?
Thanks
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      01-28-2014, 12:52 AM   #30
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Quote:
Originally Posted by HDEddie1 View Post
Hey Scott,
I noticed the flap valve is on the outboard side of our car...did you just pick up some vacuum tube (3/8" I presume) at the part store and connect with a double sided nipple to extend the stock tube?
Also, I presume drone at part throttle is non issue before the X pipe and after?
Thanks
Shop that did my exhaust extended the vaccum tube w/ a T connector, very easy.


There is no drone part throttle, in any gear at any speed, both before and after the x-pipe. I might zip tie the flaps open for a day or two just to see how it sounds.
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      03-21-2014, 10:09 PM   #31
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Where do you get x-pipes? Would a typical muffler shop carry that?
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      03-23-2014, 12:26 PM   #32
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Quote:
Originally Posted by TxBeem View Post
Where do you get x-pipes? Would a typical muffler shop carry that?
Any muffler shop should have an x-pip to fit. I got a magna flow x-pipe on mine.
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      03-23-2014, 02:55 PM   #33
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http://youtu.be/Z8FPzWR3keU

Sound clip
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      04-05-2014, 10:42 AM   #34
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Does this mod void the factory warranty? It seems like the best option currently for the 550i but I have 27k miles to go before I hit 50k... Long time to wait.
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      04-05-2014, 10:56 AM   #35
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Quote:
Originally Posted by RSBro
Does this mod void the factory warranty? It seems like the best option currently for the 550i but I have 27k miles to go before I hit 50k... Long time to wait.
Yes your factory warranty for the mufflers will be voided but that's it.
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      04-07-2014, 09:10 AM   #36
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Quote:
Originally Posted by Mbbrewer View Post
Yes your factory warranty for the mufflers will be voided but that's it.
Oh just that part?? Awesome... time to make some calls.
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