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      11-14-2019, 01:12 PM   #155
ryank382
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Quote:
Originally Posted by spool twice View Post
Thanks, not quite done. Im trying to get a shop to fabricate an x-pipe where my custom h-pipe is currently (behind rear diff).

The tone and snarly sound is due to equal-length pipes for both sides and the crossing over at the h-pipe. The stock downpipes have a difference of over 15" between front and rear banks so it causes that typical S55 truck-ish down low and buzzy up top sound.
Hey I don't mean to side track you guys but you did a great job with the sound over stock Just wanted to learn what the benefits or effects are sound wise with x-pipe scavenging you guys mentioned and also things like the diameter or banking? Whatever else there is to know lol

I have a Remus catback but honestly am gonna switch to an e92 after winter and one of the big reasons is for the sound. Hate the way this car sounds and after 4+ years I think I've had enough
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      11-14-2019, 04:07 PM   #156
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It'll be minimal compared to naturally aspirated engines, so the placement isn't as important. With that being said, and X-pipe will provide a higher-pitched sound provided the pipes leading to them are close to equal in length.

The S55 had unequal-length pipes this is why the S55 exhaust sounds the way it does stock or aftermarket where its just a deeper version of that S55 sound. Resonators or extra mufflers h-pipes or x-pipes don't help that truck-like buzzy exhaust note, only mask rasp or smooth out the same overall exhaust tone. You have to take care of that unequal-length 1st to change the overall character of the exhaust note.

Thats primarily why mine sounds different than most S55's as it's higher in pitch as it revs

Last edited by spool twice; 11-14-2019 at 04:19 PM..
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      11-14-2019, 04:45 PM   #157
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Quote:
Originally Posted by spool twice View Post
It'll be minimal compared to naturally aspirated engines, so the placement isn't as important. With that being said, and X-pipe will provide a higher-pitched sound provided the pipes leading to them are close to equal in length.

The S55 had unequal-length pipes this is why the S55 exhaust sounds the way it does stock or aftermarket where its just a deeper version of that S55 sound. Resonators or extra mufflers h-pipes or x-pipes don't help that truck-like buzzy exhaust note, only mask rasp or smooth out the same overall exhaust tone. You have to take care of that unequal-length 1st to change the overall character of the exhaust note.

Thats primarily why mine sounds different than most S55's as it's higher in pitch as it revs
Ahhh gotcha makes sense, thank you for the info!
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      11-14-2019, 05:03 PM   #158
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Quote:
Originally Posted by spool twice View Post
It'll be minimal compared to naturally aspirated engines, so the placement isn't as important. With that being said, and X-pipe will provide a higher-pitched sound provided the pipes leading to them are close to equal in length.

The S55 had unequal-length pipes this is why the S55 exhaust sounds the way it does stock or aftermarket where its just a deeper version of that S55 sound. Resonators or extra mufflers h-pipes or x-pipes don't help that truck-like buzzy exhaust note, only mask rasp or smooth out the same overall exhaust tone. You have to take care of that unequal-length 1st to change the overall character of the exhaust note.

Thats primarily why mine sounds different than most S55's as it's higher in pitch as it revs
i was looking at the unequal length issue from a soundwave point of view, for example church organ pipes can emit the same tone from pipes of different lengths as long as the diameter is increased.
this got me thinking if the shorter exhaust pipe was increased in diameter could it achieve the same result of equalising the tone
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      11-14-2019, 05:27 PM   #159
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How do exhaust system manufacturers not know this or not implement it?
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      11-14-2019, 05:39 PM   #160
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I'm sure they do, but it's probably all down to cost and time. The other side of it is if they had got it right along with many other things we'd have very little to discuss on here lol
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      11-14-2019, 06:00 PM   #161
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For sure, someone made measurements in another thread where a few of us are trying to equalize the natural even firing exhaust pulses in another thread (with success too!)

Somewhere in there was measurements of pipe diameter between both banks to possibly slow down the velocity of the pulses on one bank in an attempt to equalize the spaces once they crossover. That's really the key to getting a different sound character to the S55:

Here is my recent clip of my exhaust mod:
-stock downpipes
-stock midpipes
-center resonator/crossover delete
-custom equal-length exhaust pipes
-crossover x-pipe (previously was an h-pipe)
-stock muffler

It's basically this where the red lines represent new pipes, and the crossover now occurs behind the rear differential (the drawing is terrible I know, but its basically that...)





and a revving comparison between stock ZCP, ZCP w/ aftermarket single midpipe and secondary cat delete, and a set-up with equal-length exhaust pipes and chambered crossover section


Last edited by spool twice; 11-22-2019 at 01:22 PM..
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      01-03-2020, 04:03 PM   #162
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Just did this setup. X Pipe + Cat replacement. Added some tips too. Sounds amazing. Great mod!!
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      04-30-2020, 08:22 AM   #163
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I am also interested to know how it sounds in combination with catless downpipes. Anyone?
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      05-01-2020, 01:55 AM   #164
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Any videos of the setup? I would like to hear it. I am thinking of doing the same
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      08-06-2020, 09:21 PM   #165
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I’m on catless VRSF downpipes and I’ve ordered the 2 Magnaflow 14156. I Will post a video soon if someone is interested.
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      11-15-2020, 08:18 PM   #166
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Quote:
Originally Posted by BMWnLakers View Post
Just did this setup. X Pipe + Cat replacement. Added some tips too. Sounds amazing. Great mod!!
Hi. Do you have any sound clips?
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      05-12-2021, 07:01 PM   #167
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Anybody try x pipe in place of resonator everything else being stock
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